Odd-even parity splittings and octupole correlations in neutron-rich Ba isotopes

NASA Astrophysics Data System (ADS)

Fu, Y.; Wang, H.; Wang, L.-J.; Yao, J. M.

2018-02-01

The odd-even parity splittings in low-lying parity-doublet states of atomic nuclei with octupole correlations have usually been interpreted as rotational excitations on top of octupole vibration in the language of collective models. In this paper, we report a deep analysis of the odd-even parity splittings in the parity-doublet states of neutron-rich Ba isotopes around neutron number N =88 within a full microscopic framework of beyond-mean-field multireference covariant energy density functional theory. The dynamical correlations related to symmetry restoration and quadrupole-octupole shape fluctuation are taken into account with a generator coordinate method combined with parity, particle-number, and angular-momentum projections. We show that the behavior of odd-even parity splittings is governed by the interplay of rotation, quantum tunneling, and shape evolution. Similar to 224Ra, a picture of rotation-induced octupole shape stabilization in the positive-parity states is exhibited in the neutron-rich Ba isotopes.

Mass predictions from the Garvey-Kelson mass relations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jaenecke, J.; Masson, P.J.

Part A: The transverse Garvey-Kelson mass relation represents a homogeneous third-order partial difference equation. Procedures are described for estimating masses of nuclei with Ngreater than or equal toZ from the most general solution of this difference equation subject to a chi/sup 2/ minimization, using the recent atomic mass adjustment of Wapstra, Audi, and Hoekstra as a boundary condition. A judicious division of the input data in subsets of neutron-rich and proton-rich nuclei had to be introduced to reduce systematic errors in long-range extrapolations. Approximately 5600 mass-excess values for nuclei with 2less than or equal toZless than or equal to103, 4lessmore » than or equal toNless than or equal to157, and Ngreater than or equal toZ (except N = Z odd for A<40) have been calculated. The standard deviation for reproducing the known mass-excess values is sigma/sub m/approx. =103 keV.« less

Observing electron localization in a dissociating H2+ molecule in real time

PubMed Central

Xu, H.; Li, Zhichao; He, Feng; Wang, X.; Atia-Tul-Noor, A.; Kielpinski, D.; Sang, R. T.; Litvinyuk, I. V.

2017-01-01

Dissociation of diatomic molecules with odd number of electrons always causes the unpaired electron to localize on one of the two resulting atomic fragments. In the simplest diatomic molecule H2+ dissociation yields a hydrogen atom and a proton with the sole electron ending up on one of the two nuclei. That is equivalent to breaking of a chemical bond—the most fundamental chemical process. Here we observe such electron localization in real time by performing a pump–probe experiment. We demonstrate that in H2+ electron localization is complete in just 15 fs when the molecule’s internuclear distance reaches 8 atomic units. The measurement is supported by a theoretical simulation based on numerical solution of the time-dependent Schrödinger equation. This observation advances our understanding of detailed dynamics of molecular dissociation. PMID:28621332

Study of Even-Even/Odd-Even/Odd-Odd Nuclei in Zn-Ga-Ge Region in the Proton-Neutron IBM/IBFM/IBFFM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoshida, N.; Brant, S.; Zuffi, L.

We study the even-even, odd-even and odd-odd nuclei in the region including Zn-Ga-Ge in the proton-neutron IBM and the models derived from it: IBM2, IBFM2, IBFFM2. We describe {sup 67}Ga, {sup 65}Zn, and {sup 68}Ga by coupling odd particles to a boson core {sup 66}Zn. We also calculate the beta{sup +}-decay rates among {sup 68}Ge, {sup 68}Ga and {sup 68}Zn.

Atomic Mass and Nuclear Binding Energy for I-131 (Iodine)

NASA Astrophysics Data System (ADS)

Sukhoruchkin, S. I.; Soroko, Z. N.

This document is part of the Supplement containing the complete sets of data of Subvolume A `Nuclei with Z = 1 - 54' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope I-131 (Iodine, atomic number Z = 53, mass number A = 131).

Atomic Mass and Nuclear Binding Energy for F-22 (Fluorine)

NASA Astrophysics Data System (ADS)

Sukhoruchkin, S. I.; Soroko, Z. N.

This document is part of the Supplement containing the complete sets of data of Subvolume A `Nuclei with Z = 1 - 54' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope F-22 (Fluorine, atomic number Z = 9, mass number A = 22).

Quartetting in even-even and odd-odd N=Z nuclei

NASA Astrophysics Data System (ADS)

Sambataro, M.; Sandulescu, N.

2018-02-01

We report on a microscopic description of even-even N = Z nuclei in a formalism of quartets. Quartets are four-body correlated structures characterized by isospin T and angular momentum J. We show that the ground state correlations induced by a realistic shell model interaction can be well accounted for in terms of a restricted set of T = 0 low-J quartets, the J = 0 one playing by far a leading role among them. A conceptually similar description of odd-odd self-conjugate nuclei is given in terms of two distinct families of building blocks, one formed by the same T = 0 quartets employed for the even-even systems and the other by collective pairs with either T = 0 or T = 1. Some applications of this formalism are discussed for nuclei in the sd shell.

Weizsäcker-Skyrme-type nuclear mass formula incorporating two combinatorial radial basis function prescriptions and their application

NASA Astrophysics Data System (ADS)

Ma, Na Na; Zhang, Hai Fei; Yin, Peng; Bao, Xiao Jun; Zhang, Hong Fei

2017-08-01

Within the improved Weizsäcker-Skyrme (WS)-type nuclear mass formulas, we systematically calculated one-nucleon and two-nucleon separated energy, α-decay and β-decay energies, and the odd-even staggering (OES) of nuclear binding energies. As a result, the root-mean-square (rms) deviations of 2267 nuclei within the new improved WS-type mass formula are dropped from 493 to 167 keV, where 2267 nuclei are extracted from the atomic mass evaluation of 2012. Simultaneously, all the rms deviations of one-nucleon and two-nucleon separation energies and decay energies Qα,Qβ-,Qβ+, and QEC for more than 3000 nuclei are cut down by about 100-400 keV. Further, some basic physical observations of 988 boundary nuclei are predicted for providing reference to experiments. Finally, the overall neutron OESs and proton OESs have been systemically investigated and the residual error satisfies a normal distribution. The pairing gaps Δn and Δp of the isotopes of O, Ca, Ni, Zr, Sn, Gd, Qs, Pb, Pa, Ds and the isotonic magic chains of N =28 ,50 ,82 ,126 and even-even nuclei are also studied with dramatic improvements obtained. Especially, the rms of Δn and Δp in these nuclei have been reduced by about 200 keV. The above physical quantities show important information for nuclear charts and the features of nuclear structure.

Systematic shell-model study of β -decay properties and Gamow-Teller strength distributions in A ≈40 neutron-rich nuclei

NASA Astrophysics Data System (ADS)

Yoshida, Sota; Utsuno, Yutaka; Shimizu, Noritaka; Otsuka, Takaharu

2018-05-01

We perform large-scale shell-model calculations of β -decay properties for neutron-rich nuclei with 13 ≤Z ≤18 and 22 ≤N ≤34 , taking the first-forbidden transitions into account. The natural-parity and unnatural-parity states are calculated in the 0 ℏ ω and 1 ℏ ω model spaces, respectively, within the full s d +p f +s d g valence shell. The calculated β -decay half-lives and β -delayed neutron emission probabilities show good agreement with the experimental data. The first-forbidden transitions make a non-negligible contribution to the half-lives of N ≳28 nuclei. The low-lying Gamow-Teller strengths of even-even nuclei are considerably larger than those of the neighboring odd-A and odd-odd nuclei, strongly affecting the half-lives and neutron emission probabilities. It is shown that this even-odd effect is caused by the Jπ=1+ proton-neutron pairing interaction. We derive a formula to represent the positions of the Gamow-Teller giant resonances from the calculated strength distributions.

Time-odd mean fields in covariant density functional theory: Rotating systems

NASA Astrophysics Data System (ADS)

Afanasjev, A. V.; Abusara, H.

2010-09-01

Time-odd mean fields (nuclear magnetism) and their impact on physical observables in rotating nuclei are studied in the framework of covariant density functional theory (CDFT). It is shown that they have profound effect on the dynamic and kinematic moments of inertia. Particle number, configuration, and rotational frequency dependencies of their impact on the moments of inertia have been analyzed in a systematic way. Nuclear magnetism can also considerably modify the band crossing features such as crossing frequencies and the properties of the kinematic and dynamic moments of inertia in the band crossing region. The impact of time-odd mean fields on the moments of inertia in the regions away from band crossing only weakly depends on the relativistic mean-field parametrization, reflecting good localization of the properties of time-odd mean fields in CDFT. The moments of inertia of normal-deformed nuclei considerably deviate from the rigid-body value. On the contrary, superdeformed and hyperdeformed nuclei have the moments of inertia which are close to rigid-body value. The structure of the currents in rotating frame, their microscopic origin, and the relations to the moments of inertia have been systematically analyzed. The phenomenon of signature separation in odd-odd nuclei, induced by time-odd mean fields, has been analyzed in detail.

Energy levels for Ac-212 (Actinium-212)

NASA Astrophysics Data System (ADS)

Sukhoruchkin, S. I.; Soroko, Z. N.

This document is part of Subvolume C `Tables of Excitations of Proton- and Neutron-rich Unstable Nuclei' of Volume 19 `Nuclear States from Charged Particle Reactions' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides energy levels for atomic nuclei of the isotope Ac-212 (actinium, atomic number Z = 89, mass number A = 212).

Proton-proton correlations observed in two-proton radioactivity of 94Ag.

PubMed

Mukha, Ivan; Roeckl, Ernst; Batist, Leonid; Blazhev, Andrey; Döring, Joachim; Grawe, Hubert; Grigorenko, Leonid; Huyse, Mark; Janas, Zenon; Kirchner, Reinhard; La Commara, Marco; Mazzocchi, Chiara; Tabor, Sam L; Van Duppen, Piet

2006-01-19

The stability and spontaneous decay of naturally occurring atomic nuclei have been much studied ever since Becquerel discovered natural radioactivity in 1896. In 1960, proton-rich nuclei with an odd or an even atomic number Z were predicted to decay through one- and two-proton radioactivity, respectively. The experimental observation of one-proton radioactivity was first reported in 1982, and two-proton radioactivity has now also been detected by experimentally studying the decay properties of 45Fe (refs 3, 4) and 54Zn (ref. 5). Here we report proton-proton correlations observed during the radioactive decay of a spinning long-lived state of the lightest known isotope of silver, 94Ag, which is known to undergo one-proton decay. We infer from these correlations that the long-lived state must also decay through simultaneous two-proton emission, making 94Ag the first nucleus to exhibit one- as well as two-proton radioactivity. We attribute the two-proton emission behaviour and the unexpectedly large probability for this decay mechanism to a very large deformation of the parent nucleus into a prolate (cigar-like) shape, which facilitates emission of protons either from the same or from opposite ends of the 'cigar'.

Interference of fission amplitudes of neutron resonances and T-odd asymmetry for various prescission third particles in the ternary fission of nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kadmensky, S. G., E-mail: kadmensky@phys.vsu.ru; Bunakov, V. E.; Kadmensky, S. S.

Differential cross sections for reactions of the true ternary fission of nuclei that was induced by cold polarized neutrons were constructed with allowance of the effect that Coriolis interaction and the interference between fission amplitudes of neutron resonances excited in fissile nuclei upon incidentneutron capture by target nuclei exerted on angular distributions of prescission third particles (alpha particles, neutrons, or photons). It is shown that T -odd TRI- and ROT-type asymmetries for prescission alpha particles are associated with, respectively, the odd and even components of the Coriolis interaction-perturbed amplitude of angular distributions of particles belonging to the types indicated above.more » These asymmetries have angular distributions differing from each other and stemming from a nontrivial dependence of these components on the neutron-resonance spins J{sub s} and their projections K{sub s} onto the symmetry axis of the nucleus involved. It is shown that angular distributions of prescission photons and neutrons from reactions of the ternary fission of nuclei that is induced by cold polarized neutrons are determined by the effect of Coriolis forces exclusively. Therefore, the emerging T-odd asymmetries have a character of a ROT-type asymmetry and are universal for all target nuclei.« less

Predictions on the modes of decay of odd Z superheavy isotopes within the range 105 ≤ Z ≤ 135

NASA Astrophysics Data System (ADS)

Santhosh, K. P.; Nithya, C.

2018-05-01

The decay modes of 1051 odd Z superheavy nuclei within the range 105 ≤ Z ≤ 135, and their daughter nuclei are studied by comparing the alpha decay half-lives with the spontaneous fission half-lives. The alpha decay half-lives are calculated using the Coulomb and proximity potential model for deformed nuclei (CPPMDN) proposed by Santhosh et al. (2011) and the spontaneous fission half-lives are obtained with the shell-effect dependent formula of Santhosh et al. (Santhosh and Nithya, 2016). For a theoretical comparison, the alpha decay half-lives are also computed with the Coulomb and proximity potential model (CPPM), Viola-Seaborg-Sobiczewski semi-empirical relation (VSS), Universal curve of Poenaru et al. (UNIV), the analytical formula of Royer, and the Universal decay law of Qi et al. (UDL). The predicted decay modes and half-lives were compared with the available experimental results. The proton and neutron separation energies are calculated to identify those nuclei, which decay through proton and neutron emission. From the entire study of odd Z superheavy elements, it is seen that among 1051 nuclei, 233 nuclei exhibit proton emission and 18 nuclei exhibit neutron emission. 56 nuclei are stable against alpha decay with negative Q value for the decay. 92 nuclei show alpha decay followed by spontaneous fission and 9 nuclei show alpha decay followed by proton emission. 39 nuclei decay through full alpha chain and 595 nuclei decay through spontaneous fission. We hope that the study will be very useful for the future experimental investigations in this field.

The predictive accuracy of analytical formulas and semiclassical approaches for α decay half-lives of superheavy nuclei

NASA Astrophysics Data System (ADS)

Zhao, T. L.; Bao, X. J.; Guo, S. Q.

2018-02-01

Systematic calculations on the α decay half-lives are performed by using three analytical formulas and two semiclassical approaches. For the three analytical formulas, the experimental α decay half-lives and {Q}α values of the 66 reference nuclei have been used to obtain the coefficients. We get only four adjustable parameters to describe α decay half-lives for even-even, odd-A, and odd-odd nuclei. By comparison between the calculated values from ten analytical formulas and experimental data, it is shown that the new universal decay law (NUDL) foumula is the most accurate one to reproduce the experimental α decay half-lives of the superheavy nuclei (SHN). Meanwhile it is found that the experimental α decay half-lives of SHN are well reproduced by the Royer formula although many parameters are contained. The results show that the NUDL formula and the generalized liquid drop model (GLDM2) with consideration of the preformation factor can give fairly equivalent results for the superheavy nuclei.

Effect of exact Coulomb-exchange calculations on band-head spectra of odd-proton nuclei

NASA Astrophysics Data System (ADS)

Koh, Meng-Hock; Nurhafiza, Mohamad Nor

2017-10-01

Previous calculations of band-head energy spectra of odd-mass heavy nuclei in the Hartree-Fock-plus-Bardeen-Cooper-Schrieffer (HF-BCS) framework showed that the agreement with data is better for odd-neutron as compared to odd-proton nuclei. The reason for a poorer agreement with data for the latter have been ascribed to the possible usage of the Slater approximation in calculating the Coulomb-exchange term. In this work, we report the effect of exact Coulomb-exchange calculations on band-head energy spectra of two odd-proton nuclei (namely 237Np and 241Am) as compared to the results obtained using the Slater approximation. We performed self-consistent blocking calculations while taking the breaking of time-reversal symmetry at the mean-field level into account due to the unpaired nucleon. The SkM* and SIII parametrizations of the Skyrme interaction have been employed to approximate the effective nucleon-nucleon interaction while a seniority force is used for the pairing channel. Contrary to what was expected, our preliminary results show no improvement on the band-head spectra as compared to data when the Coulomb-exchange term is calculated exactly.

"Spin-dependent" \\varvec{μ → e} conversion on light nuclei

NASA Astrophysics Data System (ADS)

Davidson, Sacha; Kuno, Yoshitaka; Saporta, Albert

2018-02-01

The experimental sensitivity to μ → e conversion will improve by four or more orders of magnitude in coming years, making it interesting to consider the "spin-dependent" (SD) contribution to the rate. This process does not benefit from the atomic-number-squared enhancement of the spin-independent (SI) contribution, but probes different operators. We give details of our recent estimate of the spin-dependent rate, expressed as a function of operator coefficients at the experimental scale. Then we explore the prospects for distinguishing coefficients or models by using different targets, both in an EFT perspective, where a geometric representation of different targets as vectors in coefficient space is introduced, and also in three leptoquark models. It is found that comparing the rate on isotopes with and without spin could allow one to detect spin-dependent coefficients that are at least a factor of few larger than the spin-independent ones. Distinguishing among the axial, tensor and pseudoscalar operators that induce the SD rate would require calculating the nuclear matrix elements for the second two. Comparing the SD rate on nuclei with an odd proton vs. odd neutron could allow one to distinguish operators involving u quarks from those involving d quarks; this is interesting because the distinction is difficult to make for SI operators.

Projected shell model study of odd-odd f-p-g shell proton-rich nuclei

NASA Astrophysics Data System (ADS)

Palit, R.; Sheikh, J. A.; Sun, Y.; Jain, H. C.

2003-01-01

A systematic study of two-quasiparticle bands of the proton-rich odd-odd nuclei in the mass A˜70 80 region is performed using the projected shell model approach. The study includes Br, Rb, and Y isotopes with N=Z+2 and Z+4. We describe the energy spectra and electromagnetic transition strengths in terms of the configuration mixing of the angular-momentum projected multi-quasiparticle states. Signature splitting and signature inversion in the rotational bands are discussed and are shown to be well described. A preliminary study of the odd-odd N=Z nucleus 74Rb, using the concept of spontaneous symmetry breaking is also presented.

Alpha decay hindrance factors and reflection asymmetry in nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheline, R.K.; Bossinga, B.B.

1991-07-01

All available hindrance factors of alpha transitions to low-lying negative-parity states in doubly even nuclei, to odd-{ital A} parity doublets and to doubly odd parity doublet bands, are used to study the systematics of reflection asymmetry in the {ital A}{similar to}218--230 region. Special attention is given to the polarization effect of the odd particle in increasing reflection asymmetry and therefore decreasing hindrance factors to the opposite parity states of octupole bands.

Geant4 Developments for the Radon Electric Dipole Moment Search at TRIUMF

NASA Astrophysics Data System (ADS)

Rand, E. T.; Bangay, J. C.; Bianco, L.; Dunlop, R.; Finlay, P.; Garrett, P. E.; Leach, K. G.; Phillips, A. A.; Sumithrarachchi, C. S.; Svensson, C. E.; Wong, J.

2011-09-01

An experiment is being developed at TRIUMF to search for a time-reversal violating electric dipole moment (EDM) in odd-A isotopes of Rn. Extensive simulations of the experiment are being performed with GEANT4 to study the backgrounds and sensitivity of the proposed measurement technique involving the detection of γ rays emitted following the β decay of polarized Rn nuclei. GEANT4 developments for the RnEDM experiment include both realistic modelling of the detector geometry and full tracking of the radioactive β, γ, internal conversion, and x-ray processes, including the γ-ray angular distributions essential for measuring an atomic EDM.

On Closed Shells in Nuclei. II

DOE R&D Accomplishments Database

Mayer, M. G.

1949-04-01

Discussion on the use of spins and magnetic moments of the even-odd nuclei by Feenberg and Nordheim to determine the angular momentum of the eigenfunction of the odd particle; discussion of prevalence of isomerism in certain regions of the isotope chart; tabulated data on levels of square well potential, spectroscopic levels, spin term, number of states, shells and known spins and orbital assignments.

Investigation of the particle-core structure of odd-mass nuclei in the NpNn scheme

NASA Astrophysics Data System (ADS)

Bucurescu, D.; Cata, G.; Cutoiu, D.; Dragulescu, E.; Ivasu, M.; Zamfir, N. V.; Gizon, A.; Gizon, J.

1989-10-01

The NpNn scheme is applied to data related to collective band structures determined by the unique parity shell model orbitals in odd-A nuclei from the mass regions A≌80-100 and A≌130. Simple systematics are obtained which give a synthetic picture of the evolution of the particle-core coupling in these nuclear regions.

Effect of local structures on crystallization in deeply undercooled metallic glass-forming liquids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, S. Q.; Li, M. Z., E-mail: maozhili@ruc.edu.cn; Wu, Z. W.

2016-04-21

The crystallization mechanism in deeply undercooled ZrCu metallic glass-forming liquids was investigated via molecular dynamics simulations. It was found that the crystallization process is mainly controlled by the growth of crystal nuclei formed by the BCC-like atomic clusters, consistent with experimental speculations. The crystallization rate is found to relate to the number of growing crystal nuclei in the crystallization process. The crystallization rate in systems with more crystal nuclei is significantly hindered by the larger surface fractions of crystal nuclei and their different crystalline orientations. It is further revealed that in the crystallization in deeply undercooled regions, the BCC-like crystalmore » nuclei are formed from the inside of the precursors formed by the FCC-like atomic clusters, and growing at the expense of the precursors. Meanwhile, the precursors are expanding at the expense of the outside atomic clusters. This process is consistent with the so-called Ostwald step rule. The atomic structures of metallic glasses are found to have significant impact on the subsequent crystallization process. In the Zr{sub 85}Cu{sub 15} system, the stronger spatial correlation of Cu atoms could hinder the crystallization processes in deeply undercooled regions.« less

Mean-field studies of time reversal breaking states in super-heavy nuclei with the Gogny force

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robledo, L. M., E-mail: luis.robledo@uam.es

2015-10-15

Recent progress on the description of time reversal breaking (odd mass and multi-quasiparticle excitation) states in super-heavy nuclei within a mean field framework and using several flavors of the Gogny interaction is reported. The study includes ground and excited states in selected odd mass isotopes of nobelium and mendelevium as well as high K isomeric states in {sup 254}No. These are two and four-quasiparticle excitations that are treated in the same self-consistent HFB plus blocking framework as the odd mass states.

Quantization of Differences Between Atomic and Nuclear Rest Masses and Self-organization of Atoms and Nuclei

NASA Astrophysics Data System (ADS)

Gareev, F. A.; Zhidkova, I. E.

2007-03-01

We come to the conclusion that all atomic models based on either the Newton equation and the Kepler laws, or the Maxwell equations, or the Schrodinger and Dirac equations are in reasonable agreement with experimental data. We can only suspect that these equations are grounded on the same fundamental principle(s) which is (are) not known or these equations can be transformed into each other. We proposed a new mechanism of LENR: cooperative processes in the whole system nuclei + atoms + condensed matter - nuclear reactions in plasma - can occur at smaller threshold energies than the corresponding ones on free constituents. We were able to quantize phenomenologically the first time the differences between atomic and nuclear rest masses by the formula: δδM =n1/n2 X 0.0076294 (in MeV/ c^2), ni=1,2,3,.... Note that this quantization rule is justified for atoms and nuclei with different A, N and Z and the nuclei and atoms represent a coherent synchronized systems - a complex of coupled oscillators (resonators). The cooperative resonance synchronization mechanisms can explain how electron volt (atomic-) scale processes can induce and control nuclear MeV (nuclear-) scale processes and reactions., F.A. Gareev, I.E. Zhidkova, E-print arXiv Nucl-th/ 0610002 2006.

Isospin-symmetry-breaking effects in A˜70 nuclei within beyond-mean-field approach

NASA Astrophysics Data System (ADS)

Petrovici, A.; Andrei, O.

2015-02-01

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 66As and 70Br nuclei correlated with the pair structure analysis in the T=1 and T=0 channel of the involved wave functions are discussed.

Isospin-symmetry-breaking effects in A∼70 nuclei within beyond-mean-field approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 themore » 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.« less

Physics of the N=Z and N=Z+1 Nuclei in the A = 80--100 Region

NASA Astrophysics Data System (ADS)

Bucurescu, D.

2007-04-01

A review of the experimental work performed at the GASP array with the purpose of the identification and first spectroscopic measurements of the heaviest even-even N=Z and odd-A N=Z+1 nuclei (mass larger than 80) is made. Systematic experiments in this mass region led to the first study of seven such nuclei: 88Ru, 81Zr, 85Mo, 89Ru, 91Rh, 93Pd, and 95Ag, and extensive data on many other nuclei in their neighborhood. The systematic evolution of the level structures in both even-even and odd-A nuclei, between N approx Z approx 40 and N approx Z approx 47 is briefly presented. The possibility that effects of the neutron-proton pairing have been observed, as well as the type of collectivity observed in this region are discussed.

Nuclear isospin effect on α-decay half-lives

NASA Astrophysics Data System (ADS)

Akrawy, Dashty T.; Hassanabadi, H.; Hosseini, S. S.; Santhosh, K. P.

2018-07-01

The α-decay half-lives for the even-even, even-odd, odd-even and odd-odd of 356 nuclei in the range 52 ≤Zp ≤ 118 have been studied within the analytical formula of Royer and also within the modified analytical formula of Royer. We calculated the new coefficient of the Royer by fitting 356 isotopes. Also, we considered the Denisov and Khudenko formula and obtained the new coefficient for the modified Denisov and Khudenko formula. We calculated the standard deviation and the average deviation. Analytical results are compared with the experimental data. The results are in better agreement with the experimental data when the effect of the isospin considered for the parent nuclei.

Mass Measurement of 56Sc Reveals a Small A=56 Odd-Even Mass Staggering, Implying a Cooler Accreted Neutron Star Crust

DOE PAGES

Meisel, Z.; George, S.; Ahn, S.; ...

2015-10-16

We present the mass excesses of 52-57Sc, obtained from recent time-of-flight nuclear mass measurements at the National Superconducting Cyclotron Laboratory at Michigan State University. The masses of 56Sc and 57Sc were determined for the first time with atomic mass excesses of -24.85(59)((+0)(-54)) MeV and -21.0(1.3) MeV, respectively, where the asymmetric uncertainty for 56Sc was included due to possible contamination from a long-lived isomer. The 56Sc mass indicates a small odd-even mass staggering in the A = 56 mass chain towards the neutron drip line, significantly deviating from trends predicted by the global FRDM mass model and favoring trends predicted bymore » the UNEDF0 and UNEDF1 density functional calculations. Together with new shell-model calculations of the electron-capture strength function of 56Sc, our results strongly reduce uncertainties in model calculations of the heating and cooling at the 56Ti electron-capture layer in the outer crust of accreting neutron stars. We find that, in contrast to previous studies, neither strong neutrino cooling nor strong heating occurs in this layer. We conclude that Urca cooling in the outer crusts of accreting neutron stars that exhibit superbursts or high temperature steady-state burning, which are predicted to be rich in A approximate to 56 nuclei, is considerably weaker than predicted. Urca cooling must instead be dominated by electron capture on the small amounts of adjacent odd-A nuclei contained in the superburst and high temperature steady-state burning ashes. This may explain the absence of strong crust Urca cooling inferred from the observed cooling light curve of the transiently accreting x-ray source MAXI J0556-332.« less

Mass Measurement of 56Sc Reveals a Small A =56 Odd-Even Mass Staggering, Implying a Cooler Accreted Neutron Star Crust

NASA Astrophysics Data System (ADS)

Meisel, Z.; George, S.; Ahn, S.; Bazin, D.; Brown, B. A.; Browne, J.; Carpino, J. F.; Chung, H.; Cole, A. L.; Cyburt, R. H.; Estradé, A.; Famiano, M.; Gade, A.; Langer, C.; Matoš, M.; Mittig, W.; Montes, F.; Morrissey, D. J.; Pereira, J.; Schatz, H.; Schatz, J.; Scott, M.; Shapira, D.; Smith, K.; Stevens, J.; Tan, W.; Tarasov, O.; Towers, S.; Wimmer, K.; Winkelbauer, J. R.; Yurkon, J.; Zegers, R. G. T.

2015-10-01

We present the mass excesses of 52-57Sc, obtained from recent time-of-flight nuclear mass measurements at the National Superconducting Cyclotron Laboratory at Michigan State University. The masses of 56Sc and 57Sc were determined for the first time with atomic mass excesses of -24.85 (59 )(-54+0) MeV and -21.0 (1.3 ) MeV , respectively, where the asymmetric uncertainty for 56Sc was included due to possible contamination from a long-lived isomer. The 56Sc mass indicates a small odd-even mass staggering in the A =56 mass chain towards the neutron drip line, significantly deviating from trends predicted by the global FRDM mass model and favoring trends predicted by the UNEDF0 and UNEDF1 density functional calculations. Together with new shell-model calculations of the electron-capture strength function of 56Sc, our results strongly reduce uncertainties in model calculations of the heating and cooling at the 56Ti electron-capture layer in the outer crust of accreting neutron stars. We find that, in contrast to previous studies, neither strong neutrino cooling nor strong heating occurs in this layer. We conclude that Urca cooling in the outer crusts of accreting neutron stars that exhibit superbursts or high temperature steady-state burning, which are predicted to be rich in A ≈56 nuclei, is considerably weaker than predicted. Urca cooling must instead be dominated by electron capture on the small amounts of adjacent odd-A nuclei contained in the superburst and high temperature steady-state burning ashes. This may explain the absence of strong crust Urca cooling inferred from the observed cooling light curve of the transiently accreting x-ray source MAXI J0556-332.

Masses from an inhomogeneous partial difference equation with higher-order isospin contributions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masson, P.J.; Jaenecke, J.

In the present work, a mass equation obtained as the solution of an inhomogeneous partial difference equation is used to predict masses of unknown neutron-rich and proton-rich nuclei. The inhomogeneous source terms contain shell-dependent symmetry energy expressions (quadratic in isospin), and include, as well, an independently derived shell-model Coulomb energy equation which describes all known Coulomb displacement energies with a standarad deviation of sigma/sub c/ = 41 keV. Perturbations of higher order in isospin, previously recognized as a cause of systematic effects in long-range mass extrapolations, are also incorporated. The most general solutions of the inhomogeneous difference equation have beenmore » deduced from a chi/sup 2/-minimization procedure based on the recent atomic mass adjustment of Wapstra, Audi, and Hoekstra. Subjecting the solutions further to the condition of charge symmetry preserves the accuracy of Coulomb energies and allows mass predictions for nuclei with both Ngreater than or equal toZ and Z>N. The solutions correspond to a mass equation with 470 parameters. Using this equation, 4385 mass values have been calculated for nuclei with Agreater than or equal to16 (except N = Z = odd for A<40), with a standard deviation of sigma/sub m/ = 194 keV from the experimental masses. copyright 1988 Academic Press, Inc.« less

Self-consistent description of the SHFB equations for 112Sn

NASA Astrophysics Data System (ADS)

Ghafouri, M.; Sadeghi, H.; Torkiha, M.

2018-03-01

The Hartree-Fock (HF) method is an excellent approximation of the closed shell magic nuclei. Pair correlation is essential for the description of open shell nuclei and has been derived for even-even, odd-odd and even-odd nuclei. These effects are reported by Hartree-Fock with BCS (HFBCS) or Hartree-Fock-Bogolyubov (HFB). These issues have been investigated, especially in the nuclear charts, and such studies have been compared with the observed information. We compute observations such as total binding energy, charge radius, densities, separation energies, pairing gaps and potential energy surfaces for neutrons and protons, and compare them with experimental data and the result of the spherical codes. In spherical even-even neutron-rich nuclei are considered in the Skyrme-Hartree-Fock-Bogolyubov (SHFB) method with density-dependent pairing interaction. Zero-range density-dependent interactions is used in the pairing channel. We solve SHF or SHFB equations in the spatial coordinates with spherical symmetry for tin isotopes such as 112Sn. The numerical accuracy of solving equations in the coordinate space is much greater than the fundamental extensions, which yields almost precise results.

Microscopic insight into the structure of gallium isotopes

NASA Astrophysics Data System (ADS)

Verma, Preeti; Sharma, Chetan; Singh, Suram; Bharti, Arun; Khosa, S. K.

2012-07-01

Projected Shell Model technique has been applied to odd-A71-81Ga nuclei with the deformed single-particle states generated by the standard Nilsson potential. Various nuclear structure quantities have been calculated with this technique and compared with the available experimental data in the present work. The known experimental data of the yrast bands in these nuclei are persuasively described and the band diagrams obtained for these nuclei show that the yrast bands in these odd-A Ga isotopes don't belong to the single intrinsic state only but also have multi-particle states. The back-bending in moment of inertia and the electric quadrupole transitions are also calculated.

Signature inversion / chiral-twin bands in odd-odd Pr nuclei?

NASA Astrophysics Data System (ADS)

Fetea, Mirela; Thompson, Sarah

2001-10-01

Over the past few years, sufficient data have been accumulated to enable a meaningful study of the systematic trends of the signature inversion (inversion point shift in spin with increasing proton and neutron numbers in a chain of isotones / isotopes as well as the magnitude of odd-even staggering). Our aim is to understand these systematic features within the framework of particle rotor model including both a residual pn interaction and a γ deformation. Signature inversion is present in the bands of odd-odd nuclei , ^120-130Cs, ^124-132La, ^126-134Pr and ^132-136Pm and having an yrast structure built on π h_11/2ν h_11/2 orbitals. Pr isotopes seem to indicate an inversion decreasing for smaller neutron numbers, trend that is opposite for the Cs nuclei(J.F. Smith et al., Phys. Lett B 406, 7 (1997)). Why? A question that remains to be answered is if there is any relation of signature inversion to chiral twin bands (two ''look alike positive parity'' bands proposed for as in ). The lower band has signature inversion all the way up. Could these effects be related to triaxiality? Can one trust an apparent conclusion suggested by L.L. Riedinger( L.L. Riedinger, talk presented at High) Spin Physics 2001, Warsaw, Poland, February, 2001, to be published in Acta Phys. Pol.: ''signature inversion in an odd-odd band of two quasiparticles pointed along different axes is always associated with the formation of chiral twin bands''?

Left–right asymmetry in integral spectra of γ-quanta in the interaction of nuclei with polarized thermal neutrons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vesna, V. A.; Gledenov, Yu. M.; Nesvizhevsky, V. V., E-mail: nesvizhevsky@ill.eu

The paper presents results of preliminarymeasurements of the left–right asymmetry in integral spectra of γ-quanta emitted in the interaction of polarized thermal neutrons with nuclei. These results indicate that for all cases of measured statistically significant P-odd asymmetry, the left–right asymmetry coefficient is much smaller than the P-odd asymmetry coefficient. This observation is not consistent with the predictions of theoretical calculations.

Experiment S009: Nuclear Emulsion

NASA Technical Reports Server (NTRS)

Odell, F. W.; Shapiro, M. M.; Silberberg, R.; Stiller, B.; Tsao, C. H.; Durgaprasad, N.; Fichtel, C. E.; Guss, D. E.; Reames, D. V.

1971-01-01

The first exposure on a spacecraft of a nuclear emulsion apparatus designed to collect 1000 high quality tracks of heavy nuclei under a negligible thickness of matter (0.07 g/sq cm) is described. The cosmic ray detector consisted of a stack of nuclear emulsions that were designed to register at least 400 heavy nuclei tracks for each 10 hours of useful exposure. The spacecraft had to be oriented in a heads-up attitude during the 10-hour period to eliminate atmospheric albedo particles. The results are as follows: (1) a definite odd-even effect, with low abundances for elements of atomic number 7, 9, and 11; (2) a ratio O/C approximately 0.9; (3) Ne/C, Mg/C, and Si/C ratios between 0.2 and 0.3; (4) an abundance gap in the region 15 less than or equal to Z less than or equal to 19; and (5) a ratio (20 less than or equal to Z less than or equal to 28)/C 0.2, with a large concentration at Z = 26. These results are indicative that successful exposures of nuclear emulsions were obtained on the Gemini 11 mission.

Pion-less effective field theory for real and lattice nuclei

NASA Astrophysics Data System (ADS)

Bansal, Aaina; Binder, Sven; Ekström, Andreas; Hagen, Gaute; Papenbrock, Thomas

2017-09-01

We compute the medium-heavy nuclei 16O and 40Ca using pion-less effective field theory (EFT) at leading order (LO) and next-to-leading order (NLO). The low-energy coefficients of the EFT Hamiltonian are adjusted to A = 2 , 3 nuclei data from experiments, or alternatively to data from lattice QCD at unphysical pion mass mπ = 806 MeV. The EFT is implemented through discrete variable representation of finite harmonic oscillator basis. This approach ensures rapid convergence with respect to the size of the model space and allows us to compute heavier atomic and lattice nuclei. The atomic nuclei 16O and 40Ca are bound with respect to decay into alpha particles at NLO, but not at LO.

Nuclear Structure Near the N=Z Line in the A=80 Region

NASA Astrophysics Data System (ADS)

Gross, Carl J.

1996-11-01

Self-conjugate nuclei are unique laboratory systems which allow specific facets of nuclear structure to be explored. Shell gaps present in the single-particle spectra are reinforced by both proton and neutron Fermi levels. As a result of this localized occupation, proton-neutron correlations can contribute to the overall pairing energy resulting in a more stable system. Through the use of large germanium detector arrays and recoil separators, these nuclei, which are produced with extremely small fusion-evaporation cross-sections, have been observed using in-beam spectroscopic techniques only within the past decade. Typically, only the first two or three transitions have been observed. Now that even more efficient germanium arrays and recoil mass spectrometers are being coupled together, more detailed spectroscopic information may be obtained. Data will be presented for the self-conjugate odd-odd nucleus ^74Rb (D. Rudolph, et al. al.), Phys. Rev. Lett. 76, 376 (1996) whose energy level spacings are more like the even-even isotone ^74Kr than its nearest odd-odd neighbor ^76Rb. The Tz = +1/2 nuclei ^75Rb and ^77Sr (C. J. Gross, et al. al.), Phys. Rev. C 49, R580 (1994) reveal possible evidence for neutron-proton correlations at moderate spins and these data will also be presented. In addition, a systematic study of the Tz = 1 nuclei ^74Kr, ^78Sr, ^82Zr, and ^86Mo (D. Rudolph, et al. al.), Phys. Rev. C 54, 117 (1996) has been undertaken. These nuclei, reveal how the collectivity changes throughout the region. This work was supported by the U. S. Department of Energy under contracts DE-AC05-76OR00033 and DE-AC05-96OR22464.

Computational code in atomic and nuclear quantum optics: Advanced computing multiphoton resonance parameters for atoms in a strong laser field

NASA Astrophysics Data System (ADS)

Glushkov, A. V.; Gurskaya, M. Yu; Ignatenko, A. V.; Smirnov, A. V.; Serga, I. N.; Svinarenko, A. A.; Ternovsky, E. V.

2017-10-01

The consistent relativistic energy approach to the finite Fermi-systems (atoms and nuclei) in a strong realistic laser field is presented and applied to computing the multiphoton resonances parameters in some atoms and nuclei. The approach is based on the Gell-Mann and Low S-matrix formalism, multiphoton resonance lines moments technique and advanced Ivanov-Ivanova algorithm of calculating the Green’s function of the Dirac equation. The data for multiphoton resonance width and shift for the Cs atom and the 57Fe nucleus in dependence upon the laser intensity are listed.

Geant4 Simulations for the Radon Electric Dipole Moment Search at TRIUMF

NASA Astrophysics Data System (ADS)

Rand, Evan; Bangay, Jack; Bianco, Laura; Dunlop, Ryan; Finlay, Paul; Garrett, Paul; Leach, Kyle; Phillips, Andrew; Svensson, Carl; Sumithrarachchi, Chandana; Wong, James

2010-11-01

The existence of a permanent electric dipole moment (EDM) requires the violation of time-reversal symmetry (T) or, equivalently, the violation of charge conjugation C and parity P (CP). Although no particle EDM has yet been found, current theories beyond the Standard Model, e.g. multiple-Higgs theories, left-right symmetry, and supersymmetry, predict EDMs within current experimental reach. In fact, present limits on the EDMs of the neutron, electron and ^199Hg atom have significantly reduced the parameter spaces of these models. The measurement of a non-zero EDM would be a direct measurement of the violation of time-reversal symmetry, and would represent a clear signal of new physics beyond the Standard Model. Recent theoretical calculations predict large enhancements in the atomic EDMs for atoms with octupole-deformed nuclei, making odd-A Rn isotopes prime candidates for the EDM search. The Geant4 simulations presented here are essential for the development towards an EDM measurement. They provide an accurate description of γ-ray scattering and backgrounds in the experimental apparatus, and are being used to study the overall sensitivity of the RnEDM experiment at TRIUMF in Vancouver, B.C.

Vacuum low-temperature superconductivity is the essence of superconductivity - Atomic New Theory

NASA Astrophysics Data System (ADS)

Yongquan, Han

2010-10-01

The universe when the temperature closest to the Big Bang the temperature should be nuclear. Because, after the big bang, instant formation of atoms, nuclei and electrons between the absolute vacuum, the nucleus can not emit energy. (Radioactive elements, except in fact, radiation Yuan Su limited power emitted) which causes atomic nuclei and external temperature difference are so enormous that a large temperature difference reasons, all external particles became closer to the nucleus, affect the motion of electrons. When the conductor conductivity and thus affect the conductivity, the formation of resistance. Assumption that no particles affect the motion of electrons (except outside the nucleus) to form a potential difference will not change after the vector form, is now talking about the phenomenon of superconductivity, and then to introduce general, the gap between atoms in molecules or between small, valence electron number of high temperature superconducting conductors. This theory of atomic nuclei, but also explain the atomic and hydrogen bombs can remain after an explosion Why can release enormous energy reasons. Can also explain the ``super flow'' phenomenon. natural world. Tel 13241375685

Three-level mixing model for nuclear chiral rotation: Role of the planar component

NASA Astrophysics Data System (ADS)

Chen, Q. B.; Starosta, K.; Koike, T.

2018-04-01

Three- and two-level mixing models are proposed to understand the doubling of states at the same spin and parity in triaxially deformed atomic nuclei with odd numbers of protons and neutrons. The particle-rotor model for such nuclei is solved using the newly proposed basis which couples angular momenta of two valence nucleons and the rotating triaxial mean field into left-handed |L > , right-handed |R > , and planar |P > configurations. The presence and impact of the planar component is investigated as a function of the total spin for mass A ≈130 nuclei with the valence h11 /2 proton particle, valence h11 /2 neutron hole, and the maximum difference between principal axes allowed by the quadrupole deformation of the mean field. It is concluded that at each spin value the higher energy member of a doublet of states is built on the antisymmetric combination of |L > and |R > and is free of the |P > component, indicating that it is of pure chiral geometry. For the lower energy member of the doublet, the contribution of the |P > component to the eigenfunction first decreases and then increases as a function of the total spin. This trend as well as the energy splitting between the doublet states are both determined by the Hamiltonian matrix elements between the planar (|P > ) and nonplanar (|L > and |R > ) subspaces of the full Hilbert space.

Experimental evidence of the decrease of kinetic energy of hadrons in passing through atomic nuclei

NASA Technical Reports Server (NTRS)

Strugalski, Z.

1985-01-01

Hadrons with kinetic energies higher than the pion production threshold lose their kinetic energies monotonically in traversing atomic nuclei, due to the strong interactions in nuclear matter. This phenomenon is a crude analogy to the energy loss of charged particles in their passage through materials. Experimental evidence is presented.

Nuclear Structure in China 2010

NASA Astrophysics Data System (ADS)

Bai, Hong-Bo; Meng, Jie; Zhao, En-Guang; Zhou, Shan-Gui

2011-08-01

Personal view on nuclear physics research / Jie Meng -- High-spin level structures in [symbol]Zr / X. P. Cao ... [et al.] -- Constraining the symmetry energy from the neutron skin thickness of tin isotopes / Lie-Wen Chen ... [et al.] -- Wobbling rotation in atomic nuclei / Y. S. Chen and Zao-Chun Gao -- The mixing of scalar mesons and the possible nonstrange dibaryons / L. R. Dai ... [et al.] -- Net baryon productions and gluon saturation in the SPS, RHIC and LHC energy regions / Sheng-Qin Feng -- Production of heavy isotopes with collisions between two actinide nuclides / Z. Q. Feng ... [et al.] -- The projected configuration interaction method / Zao-Chun Gao and Yong-Shou Chen -- Applications of Nilsson mean-field plus extended pairing model to rare-earth nuclei / Xin Guan ... [et al.] -- Complex scaling method and the resonant states / Jian-You Guo ... [et al.] -- Probing the equation of state by deep sub-barrier fusion reactions / Hong-Jun Hao and Jun-Long Tian -- Doublet structure study in A[symbol]105 mass region / C. Y. He ... [et al.] -- Rotational bands in transfermium nuclei / X. T. He -- Shape coexistence and shape evolution [symbol]Yb / H. Hua ... [et al.] -- Multistep shell model method in the complex energy plane / R. J. Liotta -- The evolution of protoneutron stars with kaon condensate / Ang Li -- High spin structures in the [symbol]Lu nucleus / Li Cong-Bo ... [et al.] -- Nuclear stopping and equation of state / QingFeng Li and Ying Yuan -- Covariant description of the low-lying states in neutron-deficient Kr isotopes / Z. X. Li ... [et al.] -- Isospin corrections for superallowed [symbol] transitions / HaoZhao Liang ... [et al.] -- The positive-parity band structures in [symbol]Ag / C. Liu ... [et al.] -- New band structures in odd-odd [symbol]I and [symbol]I / Liu GongYe ... [et al.] -- The sd-pair shell model and interacting boson model / Yan-An Luo ... [et al.] -- Cross-section distributions of fragments in the calcium isotopes projectile fragmentation at the intermediate energy / C. W. Ma ... [et al.].Systematic study of spin assignment and dynamic moment of inertia of high-j intruder band in [symbol]In / K. Y. Ma ... [et al.] -- Signals of diproton emission from the three-body breakup channel of [symbol]Al and [symbol]Mg / Ma Yu-Gang ... [et al.] -- Uncertainties of Th/Eu and Th/Hf chronometers from nucleus masses / Z. M. Niu ... [et al.] -- The chiral doublet bands with [symbol] configuration in A[symbol]100 mass region / B. Qi ... [et al.] -- [symbol] formation probabilities in nuclei and pairing collectivity / Chong Qi -- A theoretical prospective on triggered gamma emission from [symbol]Hf[symbol] isomer / ShuiFa Shen ... [et al.] -- Study of nuclear giant resonances using a Fermi-liquid method / Bao-Xi Sun -- Rotational bands in doubly odd [symbol]Sb / D. P. Sun ... [et al.] -- The study of the neutron N=90 nuclei / W. X. Teng ... [et al.] -- Dynamical modes and mechanisms in ternary reaction of [symbol]Au+[symbol]Au / Jun-Long Tian ... [et al.] -- Dynamical study of X(3872) as a D[symbol] molecular state / B. Wang ... [et al.] -- Super-heavy stability island with a semi-empirical nuclear mass formula / N. Wang ... [et al.] -- Pseudospin partner bands in [symbol]Sb / S. Y. Wang ... [et al.] -- Study of elastic resonance scattering at CIAE / Y. B. Wang ... [et al.] -- Systematic study of survival probability of excited superheavy nuclei / C. J. Xia ... [et al.] -- Angular momentum projection of the Nilsson mean-field plus nearest-orbit pairing interaction model / Ming-Xia Xie ... [et al.] -- Possible shape coexistence for [symbol]Sm in a reflection-asymmetric relativistic mean-field approach / W. Zhang ... [et al.] -- Nuclear pairing reduction due to rotation and blocking / Zhen-Hua Zhang -- Nucleon pair approximation of the shell model: a review and perspective / Y. M. Zhao ... [et al.] -- Band structures in doubly odd [symbol]I / Y. Zheng ... [et al.] -- Lifetimes of high spin states in [symbol]Ag / Y. Zheng ... [et al.] -- Effect of tensor interaction on the shell structure of superheavy nuclei / Xian-Rong Zhou ... [et al.].

Glass-wool study of laser-induced spin currents en route to hyperpolarized Cs salt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ishikawa, Kiyoshi

2011-07-15

The nuclear spin polarization of optically pumped Cs atoms flows to the surface of Cs hydride in a vapor cell. A fine glass wool lightly coated with the salt helps greatly increase the surface area in contact with the pumped atoms and enhance the spin polarization of the salt nuclei. Even though the glass wool randomly scatters the pump light, the atomic vapor can be polarized with unpolarized light in a magnetic field. The measured enhancement in the salt enables study of the polarizations of light and atomic nuclei very near the salt surface.

Masses and β -Decay Spectroscopy of Neutron-Rich Odd-Odd Eu,162160 Nuclei: Evidence for a Subshell Gap with Large Deformation at N =98

NASA Astrophysics Data System (ADS)

Hartley, D. J.; Kondev, F. G.; Orford, R.; Clark, J. A.; Savard, G.; Ayangeakaa, A. D.; Bottoni, S.; Buchinger, F.; Burkey, M. T.; Carpenter, M. P.; Copp, P.; Gorelov, D. A.; Hicks, K.; Hoffman, C. R.; Hu, C.; Janssens, R. V. F.; Klimes, J. W.; Lauritsen, T.; Sethi, J.; Seweryniak, D.; Sharma, K. S.; Zhang, H.; Zhu, S.; Zhu, Y.

2018-05-01

The structure of deformed neutron-rich nuclei in the rare-earth region is of significant interest for both the astrophysics and nuclear structure fields. At present, a complete explanation for the observed peak in the elemental abundances at A ˜160 eludes astrophysicists, and models depend on accurate quantities, such as masses, lifetimes, and branching ratios of deformed neutron-rich nuclei in this region. Unusual nuclear structure effects are also observed, such as the unexpectedly low energies of the first 2+ levels in some even-even nuclei at N =98 . In order to address these issues, mass and β -decay spectroscopy measurements of the Eu97 160 and Eu99 162 nuclei were performed at the Californium Rare Isotope Breeder Upgrade radioactive beam facility at Argonne National Laboratory. Evidence for a gap in the single-particle neutron energies at N =98 and for large deformation (β2˜0.3 ) is discussed in relation to the unusual phenomena observed at this neutron number.

Shell-model method for Gamow-Teller transitions in heavy deformed odd-mass nuclei

NASA Astrophysics Data System (ADS)

Wang, Long-Jun; Sun, Yang; Ghorui, Surja K.

2018-04-01

A shell-model method for calculating Gamow-Teller (GT) transition rates in heavy deformed odd-mass nuclei is presented. The method is developed within the framework of the projected shell model. To implement the computation requirement when many multi-quasiparticle configurations are included in the basis, a numerical advancement based on the Pfaffian formula is introduced. With this new many-body technique, it becomes feasible to perform state-by-state calculations for the GT nuclear matrix elements of β -decay and electron-capture processes, including those at high excitation energies in heavy nuclei which are usually deformed. The first results, β- decays of the well-deformed A =153 neutron-rich nuclei, are shown as the example. The known log(f t ) data corresponding to the B (GT- ) decay rates of the ground state of 153Nd to the low-lying states of 153Pm are well described. It is further shown that the B (GT) distributions can have a strong dependence on the detailed microscopic structure of relevant states of both the parent and daughter nuclei.

Alternative method for evaluating the pair energy of nucleons in nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nurmukhamedov, A. M., E-mail: fattah52@mail.ru

2015-12-15

An alternative method for determining the odd–even effect parameter related to special features of the Casimir operator in Wigner’s mass formula for nuclei is proposed. A procedure for calculating this parameter is presented. The proposed method relies on a geometric interpretation of the Casimir operator, experimental data concerning the contribution of spin–orbit interaction to the nuclear mass for even–even and odd–odd nuclei, and systematics of energy gaps in the spectra of excited states of even–even nuclei.

Two-neutron decay within RMF+BCS approach

NASA Astrophysics Data System (ADS)

Kumawat, M.; Singh, U. K.; Saxena, G.; Kaushik, M.; Jain, S. K.

2018-05-01

A theoretical global study has been done for identifying possible candidates of 2n-radioactivity for all even and odd nuclei under proton number Z ≤ 40 by employing Relativistic Mean-Filed plus BCS (RMF+BCS) approach. We investigate two-and one-neutron separation energy, deformation, pairing energy, wave-function, potential and other ground state properties for our study of even and odd Z nuclei to find candidates of 2n-decay within Z ≤ 40. These results are found in agreement of recent experiments and consistent with other parameters of RMF and other theories.

Generalized vibrating potential model for collective excitations in spherical, deformed and superdeformed systems: (1) Atomic nuclei, (2) Metal clusters

NASA Astrophysics Data System (ADS)

Nesterenko, V. O.; Kleinig, W.

1995-01-01

The self-consistent vibrating potential model (VPM) is extended for description of Eλ collective excitations in atomic nuclei and metal clusters with practically any kind of static deformation. The model is convenient for a qualitative analysis and provides the RPA accuracy of numerical calculations. The VPM is applied to study Eλ giant resonances in spherical metal clusters and deformed and superdeformed nuclei. It is shown that the deformation splitting of superdeformed nuclei results in a very complicated ("jungle-like") structure of the resonances, which makes the experimental observation of E2 and E3 giant resonances in superdeformed nuclei quite problematic. Calculations of E1 giant resonances in spherical sodium clusters Na8, Na20 and Na40 are presented, as a test of the VPM in this field. The results are in qualitative agreement with the experimental data.

Nuclear Spin Dependent Parity Violation in Diatomic Molecules

NASA Astrophysics Data System (ADS)

Altuntas, Emine; Cahn, Sidney; Demille, David; Kozlov, Mikhail

2016-05-01

Nuclear spin-dependent parity violation (NSD-PV) effects arise from exchange of the Z0 boson between electrons and the nucleus, and from interaction of electrons with the nuclear anapole moment, a parity-odd magnetic moment. The latter scales with nucleon number of the nucleus A as A 2 / 3 , whereas the Z0 coupling is independent of A. Thus the former is the dominant source of NSD-PV for nuclei with A >= 20. We study NSD-PV effects using diatomic molecules, where signals are dramatically amplified by bringing rotational levels of opposite parity close to degeneracy in a strong magnetic field. The NSD-PV interaction matrix element is measured using a Stark-interference technique. We present results that demonstrate statistical sensitivity to NSD-PV effects surpassing that of any previous atomic parity violation measurement, using the test system 138 Ba19 F. We report our progress on measuring and cancelling systematic effects due to combination of non-reversing stray E-fields, Enr with B-field inhomogeneities. Short-term prospects for measuring the nuclear anapole moment of 137 Ba19 F are discussed. In the long term, our technique is sufficiently general and sensitive to enable measurements across a broad range of nuclei.

Nuclear Spin Dependent Parity Violation in Diatomic Molecules

NASA Astrophysics Data System (ADS)

Altuntas, Emine; Cahn, Sidney; Demille, David

2016-09-01

Nuclear spin-dependent parity violation (NSD-PV) effects arise from exchange of the Z0 boson between electrons and the nucleus, and from interaction of electrons with the nuclear anapole moment, a parity-odd magnetic moment. The latter scales with nucleon number of the nucleus A as A2/3 , whereas the Z0 coupling is independent of A. Thus the former is the dominant source of NSD-PV for nuclei with A >= 20 . We study NSD-PV effects using diatomic molecules, where signals are dramatically amplified by bringing rotational levels of opposite parity close to degeneracy in a strong magnetic field. The NSD-PV interaction matrix element is measured using a Stark-interference technique. We present results that demonstrate statistical sensitivity to NSD-PV effects surpassing that of any previous atomic parity violation measurement, using the test system 138Ba19F. We report our progress on measuring and cancelling systematic effects due to combination of non-reversing stray E-fields, Enr with B-field inhomogeneities. Short-term prospects for measuring the nuclear anapole moment of 137Ba19F are discussed. In the long term, our technique is sufficiently general and sensitive to enable measurements across a broad range of nuclei.

Nuclear Spin Dependent Parity Violation in Diatomic Molecules

NASA Astrophysics Data System (ADS)

Altuntas, Emine; Ammon, Jeffrey; Cahn, Sidney; Demille, David; Kozlov, Mikhail; Paolino, Richard

2015-05-01

Nuclear spin-dependent parity violation (NSD-PV) effects arise from exchange of the Z0 boson between electrons and the nucleus, and from interaction of electrons with the nuclear anapole moment, a parity-odd magnetic moment. The latter scales with nucleon number of the nucleus A as A 2 / 3 , whereas the Z0 coupling is independent of A. Thus the former is the dominant source of NSD-PV for nuclei with A >= 20. We study NSD-PV effects using diatomic molecules, where signals are dramatically amplified by bringing rotational levels of opposite parity close to degeneracy in a strong magnetic field. Using a Stark-interference technique we measure the NSD-PV interaction matrix element. We present results that demonstrate statistical sensitivity to NSD-PV effects surpassing that of any previous atomic parity violation measurement, using the test system 138Ba19F. We also discuss investigations of systematics due to non-reversing stray E-fields, Enr together with B-field inhomogeneities, and short-term prospects for measuring the nuclear anapole moment of 137Ba. In the long term, our technique is sufficiently general and sensitive to enable measurements across a broad range of nuclei.

Designer Nuclei--Making Atoms that Barely Exist

ERIC Educational Resources Information Center

Jones, Kate L.; Nazarewicz, Witold

2010-01-01

The physics of nuclei is not a democratic field. It has to be said, some nuclei are just more interesting than others. And some are more useful than others, either to explain the origins of the elements, or the nature of matter itself, or for uses in medicine and other applied fields. The trick is to work out which nuclei are going to be the most…

Large-scale evaluation of β -decay rates of r -process nuclei with the inclusion of first-forbidden transitions

NASA Astrophysics Data System (ADS)

Marketin, T.; Huther, L.; Martínez-Pinedo, G.

2016-02-01

Background: r -process nucleosynthesis models rely, by necessity, on nuclear structure models for input. Particularly important are β -decay half-lives of neutron-rich nuclei. At present only a single systematic calculation exists that provides values for all relevant nuclei making it difficult to test the sensitivity of nucleosynthesis models to this input. Additionally, even though there are indications that their contribution may be significant, the impact of first-forbidden transitions on decay rates has not been systematically studied within a consistent model. Purpose: Our goal is to provide a table of β -decay half-lives and β -delayed neutron emission probabilities, including first-forbidden transitions, calculated within a fully self-consistent microscopic theoretical framework. The results are used in an r -process nucleosynthesis calculation to asses the sensitivity of heavy element nucleosynthesis to weak interaction reaction rates. Method: We use a fully self-consistent covariant density functional theory (CDFT) framework. The ground state of all nuclei is calculated with the relativistic Hartree-Bogoliubov (RHB) model, and excited states are obtained within the proton-neutron relativistic quasiparticle random phase approximation (p n -RQRPA). Results: The β -decay half-lives, β -delayed neutron emission probabilities, and the average number of emitted neutrons have been calculated for 5409 nuclei in the neutron-rich region of the nuclear chart. We observe a significant contribution of the first-forbidden transitions to the total decay rate in nuclei far from the valley of stability. The experimental half-lives are in general well reproduced for even-even, odd-A , and odd-odd nuclei, in particular for short-lived nuclei. The resulting data table is included with the article as Supplemental Material. Conclusions: In certain regions of the nuclear chart, first-forbidden transitions constitute a large fraction of the total decay rate and must be taken into account consistently in modern evaluations of half-lives. Both the β -decay half-lives and β -delayed neutron emission probabilities have a noticeable impact on the results of heavy element nucleosynthesis models.

Computer Model Of Fragmentation Of Atomic Nuclei

NASA Technical Reports Server (NTRS)

Wilson, John W.; Townsend, Lawrence W.; Tripathi, Ram K.; Norbury, John W.; KHAN FERDOUS; Badavi, Francis F.

1995-01-01

High Charge and Energy Semiempirical Nuclear Fragmentation Model (HZEFRG1) computer program developed to be computationally efficient, user-friendly, physics-based program for generating data bases on fragmentation of atomic nuclei. Data bases generated used in calculations pertaining to such radiation-transport applications as shielding against radiation in outer space, radiation dosimetry in outer space, cancer therapy in laboratories with beams of heavy ions, and simulation studies for designing detectors for experiments in nuclear physics. Provides cross sections for production of individual elements and isotopes in breakups of high-energy heavy ions by combined nuclear and Coulomb fields of interacting nuclei. Written in ANSI FORTRAN 77.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Colò, G., E-mail: gianluca.colo@mi.infn.it; Baldo, M.; Bortignon, P. F.

In this contribution, we report some recent progress in our understanding of particle-vibration coupling (PVC) in nuclei. In particular, we first review the formal development that has allowed some of us to deduce the PVC equations within the Green’s functionmethod. Applications are then discussed, both in the case of single-particle states and giant resonances in magic nuclei. We also present a new model that extends the PVC ansatz and is meant to account for the complete low-lying spectra of odd nuclei.

Hidden momentum of electrons, nuclei, atoms, and molecules

NASA Astrophysics Data System (ADS)

Cameron, Robert P.; Cotter, J. P.

2018-04-01

We consider the positions and velocities of electrons and spinning nuclei and demonstrate that these particles harbour hidden momentum when located in an electromagnetic field. This hidden momentum is present in all atoms and molecules, however it is ultimately canceled by the momentum of the electromagnetic field. We point out that an electron vortex in an electric field might harbour a comparatively large hidden momentum and recognize the phenomenon of hidden hidden momentum.

Nuclear chirality, a model and the data

NASA Astrophysics Data System (ADS)

Starosta, K.; Koike, T.

2017-09-01

In the last decade, the manifestation of chirality in atomic nuclei has become the subject of numerous experimental and theoretical studies. The common feature of current model calculations is that the chiral geometry of angular momentum coupling is extracted from expectation values of orientation operators, rather than being a starting point in construction of a model. However, using the particle-hole coupling model for triaxial odd-odd nuclei it is possible to construct a basis which contains right-handed, left-handed and planar states of angular momentum coupling. If this basis is used, the chirality is an explicit rather than an extracted feature as in any other models with non-chiral bases. The time-reversal symmetry, which relates the basis states of opposite handedness, can be used to reduce the dimension of matrices for diagonalization of the model Hamiltonian, proving the effectiveness of this approach. Moreover, the final model eigenstate wave functions show a concentration of amplitudes among a relatively small number (˜1%) of components compared to the full model space. In that sense, the ‘chiral’ basis provides a useful tool to examine model predictions providing direct insight into the structure of doublet states. In this work, similarities and differences between the rotational behaviour of an axial and triaxial body provide a starting point for derivation of the basis optimal for valence nucleon coupling to an axial and a triaxial core. The derived ‘chiral’ basis is optimal for coupling of a valence particle and hole to the triaxial core. Model predictions are presented and discussed. A comprehensive review of current experimental data on observed chiral band candidates is also provided.

Nuclei and the Unitary Limit

NASA Astrophysics Data System (ADS)

Hammer, H.-W.

2018-07-01

Few-body systems with large scattering length display universal properties which are independent of the details of short-distance dynamics. These features include universal correlations between few-body observables and a geometric spectrum of three- and higher-body bound states. They can be observed in a wide range of systems from ultracold atoms to hadrons and nuclei. In this contribution, we review universality in nuclei dominated by few-body physics. In particular, we discuss halo nuclei and the description of light nuclei in a strict expansion around the unitary limit of infinite scattering length.

Nuclear spectroscopy of r-process nuclei around N = 126 using KISS

NASA Astrophysics Data System (ADS)

Hirayama, Y.; Watanabe, Y. X.; Miyatake, H.; Schury, P.; Wada, M.; Oyaizu, M.; Kakiguchi, Y.; Mukai, M.; Kimura, S.; Ahmed, M.; Jeong, S. C.; Moon, J. Y.; Park, J. H.

2017-09-01

The beta-decay properties and atomic mass of nuclei with neutron magic number of N = 126 are considered critical for understanding the production of heavy elements such as gold and platinum at astrophysical sites. We will produce and measure the half-lives and masses of the nuclei with Z = 74-77 around N = 126 by using the multinucleon transfer (MNT) reaction of ^{136} Xe/ ^{238} U beams and ^{198} Pt target system. For this purpose, we have constructed the KEK Isotope Separation System (KISS) at RIKEN RIBF facility. KISS consists of an argon gas cell based laser ion source (atomic number selection) and an isotope separation on-line (ISOL) (mass number selection), to produce pure low-energy beams of neutron-rich isotopes around N = 126 . We performed the on-line tests to study the basic properties of the KISS and, successfully extracted laser-ionized nuclei around N = 126.

Coupled-cluster computations of atomic nuclei

NASA Astrophysics Data System (ADS)

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.

Structure of positive parity bands and observation of magnetic rotation in 108Ag

NASA Astrophysics Data System (ADS)

Sethi, Jasmine; Palit, R.

2015-10-01

The interplay of nuclear forces among the neutron particles (holes) and proton holes (particles) in the odd-odd nuclei gives rise to a variety of shapes and hence novel modes of excitations. The odd-odd nuclei in the A ~ 110 region have proton holes in the g9/2 orbital and the neutron particles in the h11/2 orbitals. A systematic study of shears mechanism in A ~ 110 region indicates the presence of magnetic rotation (MR) phenomenon in Ag and In isotopes. Therefore, the structure of doubly odd 108Ag nucleus was probed in two different reactions, i.e, 100Mo(11B, 4n)108Ag at 39 MeV and 94Zr(18O, p3n)108Ag at 72 MeV beam energies. The emitted γ-rays were detected using the Indian National Gamma Array (INGA) at TIFR, Mumbai. A significant number of new transitions and energy levels were identified. Lifetime measurements, using the Doppler shift attenuation method, have been carried out for a positive parity dipole band. Tilted Axis Cranking (TAC) calculations have been performed for two positive parity dipole bands.

Effective field theory of emergent symmetry breaking in deformed atomic nuclei

DOE PAGES

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

Systematics of ground state multiplets of atomic nuclei in the delta-interaction approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Imasheva, L. T.; Ishkhanov, B. S.; Stepanov, M. E., E-mail: stepanov@depni.sinp.msu.ru

2015-12-15

Pairing forces between nucleons in an atomic nucleus strongly influence its structure. One of the manifestations of pair interaction is the ground state multiplet (GSM) formation in the spectrum of low-lying excited states of even–even nuclei. The value of GSM splitting is determined by the value of pair interaction of nucleons; for each isotope, it can be estimated on the basis of experimental nuclear masses. The quality of this estimate is characterized by the degree of reproduction of GSM levels in the nucleus. The GSM systematics in even–even nuclei with a pair of identical nucleons in addition to the filledmore » nuclear core is considered on the basis of delta interaction.« less

Deformation effect on spectral statistics of nuclei

NASA Astrophysics Data System (ADS)

Sabri, H.; Jalili Majarshin, A.

2018-02-01

In this study, we tried to get significant relations between the spectral statistics of atomic nuclei and their different degrees of deformations. To this aim, the empirical energy levels of 109 even-even nuclei in the 22 ≤ A ≤ 196 mass region are classified as their experimental and calculated quadrupole, octupole, hexadecapole and hexacontatetrapole deformations values and analyzed by random matrix theory. Our results show an obvious relation between the regularity of nuclei and strong quadrupole, hexadecapole and hexacontatetrapole deformations and but for nuclei that their octupole deformations are nonzero, we have observed a GOE-like statistics.

Neutron and weak-charge distributions of the 48Ca nucleus

DOE PAGES

Hagen, Gaute; Forssen, Christian; Nazarewicz, Witold; ...

2015-11-02

What is the size of the atomic nucleus? This deceivably simple question is difficult to answer. Although the electric charge distributions in atomic nuclei were measured accurately already half a century ago, our knowledge of the distribution of neutrons is still deficient. In addition to constraining the size of atomic nuclei, the neutron distribution also impacts the number of nuclei that can exist and the size of neutron stars. We present an ab initio calculation of the neutron distribution of the neutron-rich nucleus 48Ca. We show that the neutron skin (difference between the radii of the neutron and proton distributions)more » is significantly smaller than previously thought. We also make predictions for the electric dipole polarizability and the weak form factor; both quantities that are at present targeted by precision measurements. Here, based on ab initio results for 48Ca, we provide a constraint on the size of a neutron star.« less

Systematics of α-decay fine structure in odd-mass nuclei based on a finite-range nucleon-nucleon interaction

NASA Astrophysics Data System (ADS)

Adel, A.; Alharbi, T.

2018-07-01

A systematic study on α-decay fine structure is presented for odd-mass nuclei in the range 83 ≤ Z ≤ 92. The α-decay partial half-lives and branching ratios to the ground and excited states of daughter nuclei are calculated in the framework of the Wentzel-Kramers-Brillouin (WKB) approximation with the implementation of the Bohr-Sommerfeld quantization condition. The microscopic α-daughter potential is obtained using the double-folding model with a realistic M3Y-Paris nucleon-nucleon (NN) interaction. The exchange potential, which accounts for the knock-on exchange of nucleons between the interacting nuclei, is calculated using the finite-range exchange NN interaction which is essentially a much better approximation as compared to the zero-range pseudo-potential adopted in the usual double-folding calculations. Our calculations of α-decay fine structure have been improved by considering the preformation factor extracted from the recently proposed cluster formation model on basis of the binding energy difference. The computed partial half-lives and branching ratios are compared with the recent experimental data and they are in good agreement.

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.

Collective Band Structures in the Neutron-Rich 107,109Ru Nuclei

NASA Astrophysics Data System (ADS)

Zhu, Sheng-jiang; Gan, Cui-yun; J, Hamilton H.; A, Ramayya V.; B, Babu R. S.; M, Sakhaee; W, Ma C.; Long, Gui-lu; Deng, Jing-kang; Zhu, Ling-yan; Li, Ming; Yang, Li-ming; J, Komicki; J, Cole D.; R, Aryaeinejad; Y, Dardenne K.; M, Drigert W.; J, Rasmussen O.; M, Stoyer A.; S, Chu Y.; K, Gregorich E.; M, Mohar F.; S, Prussin G.; I, Lee Y.; N, Johnson R.; F, McGowan K.

1998-11-01

The levels in neutron-rich odd-A 107,109Ru nuclei have been investigated by using γ-γ- and γ-γ-γ-coincidence studies of the prompt γ-rays from the spontaneous fission of 252Cf. The ground state bands and the negative parity bands are identified and expanded in both nuclei. Triaxial rotor plus particle model calculations indicate the ground state bands originate from ν(d5/2 + g7/2) quasiparticle configurations and the negative parity bands are from νh11/2 orbital.

Coupled channels description of the α-decay fine structure

NASA Astrophysics Data System (ADS)

Delion, D. S.; Ren, Zhongzhou; Dumitrescu, A.; Ni, Dongdong

2018-05-01

We review the coupled channels approach of α transitions to excited states. The α-decaying states are identified as narrow outgoing Gamow resonances in an α-daughter potential. The real part of the eigenvalue corresponds to the Q-value, while the imaginary part determines the half of the total α-decay width. We first review the calculations describing transitions to rotational states treated by the rigid rotator model, in even–even, odd-mass and odd–odd nuclei. It is found that the semiclassical method overestimates the branching ratios to excited 4+ for some even–even α-emitters and fails in explaining the unexpected inversion of branching ratios of some odd-mass nuclei, while the coupled-channels results show good agreement with the experimental data. Then, we review the coupled channels method for α-transitions to 2+ vibrational and transitional states. We present the results of the Coherent State Model that describes in a unified way the spectra of vibrational, transitional and rotational nuclei. We evidence general features of the α-decay fine structure, namely the linear dependence between α-intensities and excitation energy, the linear correlation between the strength of the α-core interaction and spectroscopic factor, and the inverse correlation between the nuclear collectivity, given by electromagnetic transitions, and α-clustering.

Semiclassical unified description of wobbling motion in even-even and even-odd nuclei

NASA Astrophysics Data System (ADS)

Raduta, A. A.; Poenaru, R.; Ixaru, L. Gr.

2017-11-01

A unitary description for wobbling motion in even-even and even-odd nuclei is presented. In both cases compact formulas for wobbling frequencies are derived. The accuracy of the harmonic approximation is studied for the yrast as well as for the excited bands in the even-even case. Important results for the structure of the wave function and its behavior inside the two wells of the potential energy function corresponding to the Bargmann representation are pointed out. Applications to 158Er and 163Lu reveal a very good agreement with available data. Indeed, the yrast energy levels in the even-even case and the first four triaxial superdeformed bands, TSD1, TSD2, TSD3, and TSD4, are realistically described. Also, the results agree with the data for the E 2 and M 1 intra- as well as interband transitions. Perspectives for the formalism development and an extensive application to several nuclei from various regions of the nuclides chart are presented.

Derivatives in discrete mathematics: a novel graph-theoretical invariant for generating new 2/3D molecular descriptors. I. Theory and QSPR application

NASA Astrophysics Data System (ADS)

Marrero-Ponce, Yovani; Santiago, Oscar Martínez; López, Yoan Martínez; Barigye, Stephen J.; Torrens, Francisco

2012-11-01

In this report, we present a new mathematical approach for describing chemical structures of organic molecules at atomic-molecular level, proposing for the first time the use of the concept of the derivative ( partial ) of a molecular graph (MG) with respect to a given event ( E), to obtain a new family of molecular descriptors (MDs). With this purpose, a new matrix representation of the MG, which generalizes graph's theory's traditional incidence matrix, is introduced. This matrix, denominated the generalized incidence matrix, Q, arises from the Boolean representation of molecular sub- graphs that participate in the formation of the graph molecular skeleton MG and could be complete (representing all possible connected sub-graphs) or constitute sub-graphs of determined orders or types as well as a combination of these. The Q matrix is a non-quadratic and unsymmetrical in nature, its columns ( n) and rows ( m) are conditions (letters) and collection of conditions (words) with which the event occurs. This non-quadratic and unsymmetrical matrix is transformed, by algebraic manipulation, to a quadratic and symmetric matrix known as relations frequency matrix, F, which characterizes the participation intensity of the conditions (letters) in the events (words). With F, we calculate the derivative over a pair of atomic nuclei. The local index for the atomic nuclei i, Δ i , can therefore be obtained as a linear combination of all the pair derivatives of the atomic nuclei i with all the rest of the j's atomic nuclei. Here, we also define new strategies that generalize the present form of obtaining global or local (group or atom-type) invariants from atomic contributions (local vertex invariants, LOVIs). In respect to this, metric (norms), means and statistical invariants are introduced. These invariants are applied to a vector whose components are the values Δ i for the atomic nuclei of the molecule or its fragments. Moreover, with the purpose of differentiating among different atoms, an atomic weighting scheme (atom-type labels) is used in the formation of the matrix Q or in LOVIs state. The obtained indices were utilized to describe the partition coefficient (Log P) and the reactivity index (Log K) of the 34 derivatives of 2-furylethylenes. In all the cases, our MDs showed better statistical results than those previously obtained using some of the most used families of MDs in chemometric practice. Therefore, it has been demonstrated to that the proposed MDs are useful in molecular design and permit obtaining easier and robust mathematical models than the majority of those reported in the literature. All this range of mentioned possibilities open "the doors" to the creation of a new family of MDs, using the graph derivative, and avail a new tool for QSAR/QSPR and molecular diversity/similarity studies.

Derivatives in discrete mathematics: a novel graph-theoretical invariant for generating new 2/3D molecular descriptors. I. Theory and QSPR application.

PubMed

Marrero-Ponce, Yovani; Santiago, Oscar Martínez; López, Yoan Martínez; Barigye, Stephen J; Torrens, Francisco

2012-11-01

In this report, we present a new mathematical approach for describing chemical structures of organic molecules at atomic-molecular level, proposing for the first time the use of the concept of the derivative ([Formula: see text]) of a molecular graph (MG) with respect to a given event (E), to obtain a new family of molecular descriptors (MDs). With this purpose, a new matrix representation of the MG, which generalizes graph's theory's traditional incidence matrix, is introduced. This matrix, denominated the generalized incidence matrix, Q, arises from the Boolean representation of molecular sub-graphs that participate in the formation of the graph molecular skeleton MG and could be complete (representing all possible connected sub-graphs) or constitute sub-graphs of determined orders or types as well as a combination of these. The Q matrix is a non-quadratic and unsymmetrical in nature, its columns (n) and rows (m) are conditions (letters) and collection of conditions (words) with which the event occurs. This non-quadratic and unsymmetrical matrix is transformed, by algebraic manipulation, to a quadratic and symmetric matrix known as relations frequency matrix, F, which characterizes the participation intensity of the conditions (letters) in the events (words). With F, we calculate the derivative over a pair of atomic nuclei. The local index for the atomic nuclei i, Δ(i), can therefore be obtained as a linear combination of all the pair derivatives of the atomic nuclei i with all the rest of the j's atomic nuclei. Here, we also define new strategies that generalize the present form of obtaining global or local (group or atom-type) invariants from atomic contributions (local vertex invariants, LOVIs). In respect to this, metric (norms), means and statistical invariants are introduced. These invariants are applied to a vector whose components are the values Δ(i) for the atomic nuclei of the molecule or its fragments. Moreover, with the purpose of differentiating among different atoms, an atomic weighting scheme (atom-type labels) is used in the formation of the matrix Q or in LOVIs state. The obtained indices were utilized to describe the partition coefficient (Log P) and the reactivity index (Log K) of the 34 derivatives of 2-furylethylenes. In all the cases, our MDs showed better statistical results than those previously obtained using some of the most used families of MDs in chemometric practice. Therefore, it has been demonstrated to that the proposed MDs are useful in molecular design and permit obtaining easier and robust mathematical models than the majority of those reported in the literature. All this range of mentioned possibilities open "the doors" to the creation of a new family of MDs, using the graph derivative, and avail a new tool for QSAR/QSPR and molecular diversity/similarity studies.

Heaviest Nuclei: New Element with Atomic Number 117

ScienceCinema

Oganessian, Yuri

2018-01-24

One of the fundamental outcomes of the nuclear shell model is the prediction of the 'stability islands' in the domain of the hypothetical super heavy elements. The talk is devoted to the experimental verification of these predictions - the synthesis and study of both the decay and chemical properties of the super heavy elements. The discovery of a new chemical element with atomic number Z=117 is reported. The isotopes 293117 and 294117 were produced in fusion reactions between 48Ca and 249Bk. Decay chains involving 11 new nuclei were identified by means of the Dubna gas-filled recoil separator. The measured decay properties show a strong rise of stability for heavier isotopes with Z =111, validating the concept of the long sought island of enhanced stability for heaviest nuclei.

Colloquium: Laser probing of neutron-rich nuclei in light atoms

NASA Astrophysics Data System (ADS)

Lu, Z.-T.; Mueller, P.; Drake, G. W. F.; Nörtershäuser, W.; Pieper, Steven C.; Yan, Z.-C.

2013-10-01

The neutron-rich He6 and He8 isotopes exhibit an exotic nuclear structure that consists of a tightly bound He4-like core with additional neutrons orbiting at a relatively large distance, forming a halo. Recent experimental efforts have succeeded in laser trapping and cooling these short-lived, rare helium atoms and have measured the atomic isotope shifts along the He4-He6-He8 chain by performing laser spectroscopy on individual trapped atoms. Meanwhile, the few-electron atomic structure theory, including relativistic and QED corrections, has reached a comparable degree of accuracy in the calculation of the isotope shifts. In parallel efforts, also by measuring atomic isotope shifts, the nuclear charge radii of lithium and beryllium isotopes have been studied. The techniques employed were resonance ionization spectroscopy on neutral, thermal lithium atoms and collinear laser spectroscopy on beryllium ions. Combining advances in both atomic theory and laser spectroscopy, the charge radii of these light halo nuclei have now been determined for the first time independent of nuclear structure models. The results are compared with the values predicted by a number of nuclear structure calculations and are used to guide our understanding of the nuclear forces in the extremely neutron-rich environment.

Inclusion of particle-vibration coupling in the Fayans functional: Odd-even mass differences of semimagic nuclei

NASA Astrophysics Data System (ADS)

Saperstein, E. E.; Baldo, M.; Pankratov, S. S.; Tolokonnikov, S. V.

2018-05-01

A method is presented to evaluate the particle-phonon coupling (PC) corrections to the single-particle energies in semimagic nuclei, based on the direct solution of the Dyson equation with PC-corrected mass operator. It is used for finding the odd-even mass difference between even Pb and Sn isotopes and their odd-proton neighbors. The Fayans energy density functional DF3-a is used, which gives rather highly accurate predictions for these mass differences already at the mean-field level. In the case of the lead chain, account for the PC corrections induced by the low-lying phonons 21+ and 31- makes agreement of the theory with the experimental data significantly better. For the tin chain, the situation is not so definite. In this case, the PC corrections make agreement better in the case of the addition mode but they spoil the agreement for the removal mode. We discuss the reason for such a discrepancy.

Phonon-particle coupling effects in odd-even mass differences of semi-magic nuclei

NASA Astrophysics Data System (ADS)

Saperstein, E. E.; Baldo, M.; Pankratov, S. S.; Tolokonnikov, S. V.

2017-11-01

A method to evaluate the particle-phonon coupling (PC) corrections to the single-particle energies in semi-magic nuclei, based on a direct solving the Dyson equation with PC corrected mass operator, is used for finding the odd-even mass difference between 18 even Pb isotopes and their odd-proton neighbors. The Fayans energy density functional (EDF) DF3-a is used which gives rather high accuracy of the predictions for these mass differences already on the mean-field level, with the average deviation from the existing experimental data equal to 0.389 MeV. It is only a bit worse than the corresponding value of 0.333 MeV for the Skyrme EDF HFB-17, which belongs to a family of Skyrme EDFs with the highest overall accuracy in describing the nuclear masses. Account for the PC corrections induced by the low-laying phonons 2 1 + and 3 1 - significantly diminishes the deviation of the theory from the data till 0.218 MeV.

Analysis of decay chains of superheavy nuclei produced in the 249Bk+48Ca and 243Am+48Ca reactions

NASA Astrophysics Data System (ADS)

Zlokazov, V. B.; Utyonkov, V. K.

2017-07-01

The analysis of decay chains starting at superheavy nuclei 293Ts and 289Mc is presented. The spectroscopic properties of nuclei identified during the experiments using the 249Bk+48Ca and 243Am+48Ca reactions studied at the gas-filled separators DGFRS, TASCA and BGS are considered. We present the analysis of decay data using widely adopted statistical methods and applying them to the short decay chains of parent odd-Z nuclei. We find out that the recently suggested method of analyzing decay chains by Forsberg et al may lead to questionable conclusions when applied for the analysis of radioactive decays. Our discussion demonstrates reasonable congruence of α-particle energies and decay times of nuclei assigned to isotopes 289Mc, 285Nh and 281Rg observed in both reactions.

Dipole response of the odd-proton nucleus 205Tl up to the neutron-separation energy

NASA Astrophysics Data System (ADS)

Benouaret, N.; Beller, J.; Pai, H.; Pietralla, N.; Ponomarev, V. Yu; Romig, C.; Schnorrenberger, L.; Zweidinger, M.; Scheck, M.; Isaak, J.; Savran, D.; Sonnabend, K.; Raut, R.; Rusev, G.; Tonchev, A. P.; Tornow, W.; Weller, H. R.; Kelley, J. H.

2016-11-01

The low-lying electromagnetic dipole strength of the odd-proton nuclide 205Tl has been investigated up to the neutron separation energy exploiting the method of nuclear resonance fluorescence. In total, 61 levels of 205Tl have been identified. The measured strength distribution of 205Tl is discussed and compared to those of even-even and even-odd mass nuclei in the same mass region as well as to calculations that have been performed within the quasi-particle phonon model.

Triaxiality in the odd-A nuclei 109-117I studied through a microscopic rotationparticle coupling

NASA Astrophysics Data System (ADS)

Modi, Swati

2018-05-01

A systematic study of ground state spectrum with the triaxial deformation γ for odd-A Iodine isotopes 109-117I is carried out with the nonadiabatic quasiparticle approach. The rotation-particle coupling is accomplished microscopically such that the matrix elements of a particle-plus-rotor system are written in terms of the rotor energies. The 5/2+ state is confirmed as ground state for odd-A 111-117I and also coming out as lowest in energy for 109I.

Predictions of nuclear charge radii

NASA Astrophysics Data System (ADS)

Bao, M.; Lu, Y.; Zhao, Y. M.; Arima, A.

2016-12-01

The nuclear charge radius is a fundamental property of an atomic nucleus. In this article we study the predictive power of empirical relations for experimental nuclear charge radii of neighboring nuclei and predict the unknown charge radii of 1085 nuclei based on the experimental CR2013 database within an uncertainty of 0.03 fm.

The Atomic Mass Evaluation (AME2012): Status and Perspectives

NASA Astrophysics Data System (ADS)

Kondev, F. G.; Audi, G.; Wang, M.; Xu, X.; Wapstra, A. H.; MacCormick, M.; Pfeiffer, B.

2013-10-01

The atomic mass is a fundamental property of the nucleus that has wide applications in natural sciences and technology. The new evaluated mass table, AME2012, has been recently published as a collaborative effort between scientists from China, Europe and USA, under the leadership of G. Audi. It represents a significant update of the previous AME2003 evaluation by considering a large number of precise experimental results obtained at existing Penning Trap and Storage Ring facilities, thus expending the region of experimentally known masses towards exotic neutron- and proton-rich nuclei. Since the presence of isomers plays an important role in determining the masses of many nuclei, a complementary database, NUBASE2012, that contains the isomer-level properties for all nuclei was also developed. This presentation will briefly review recent achievements of the collaboration, present on-going activities, and reflect on ideas for future developments and challenges in the field of evaluation of atomic masses. The work at ANL was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.

Pairing and (9/2)n configuration in nuclei in the 208Pb region

NASA Astrophysics Data System (ADS)

Stepanov, M.; Imasheva, L.; Ishkhanov, B.; Tretyakova, T.

2018-04-01

Excited states in low-energy spectra in nuclei near 208Pb are considered. The pure (j = 9/2)n configuration approximation with delta-force is used for ground state multiplet calculations. The multiplet splitting is determined by the pairing energy, which can be defined from the even-odd straggering of the nuclear masses. For the configurations with more than two valence nucleons, the seniority scheme is used. The results of the calculations agree with the experimental data for both stable and exotic nuclei within 0.06-6.16%. Due to simplicity and absence of the fitted parameters, the model can be easily applied for studies of nature of the excited states in a wide range of nuclei.

Failure of the gross theory of beta decay in neutron deficient nuclei

DOE PAGES

Firestone, R. B.; Schwengner, R.; Zuber, K.

2015-05-28

The neutron deficient isotopes 117-121Xe, 117-124Cs, and 122-124Ba were produced by a beam of 28Si from the LBNL SuperHILAC on a target of natMo. The isotopes were mass separated and their beta decay schemes were measured with a Total Absorption Spectrometer (TAS). The beta strengths derived from these data decreased dramatically to levels above ≈1 MeV for the even-even decays; 3–4 MeV for even-Z, odd-N decays; 4–5 MeV for the odd-Z, even-N decays; and 7–8 MeV for the odd-Z, odd-N decays. The decreasing strength to higher excitation energies in the daughters contradicts the predictions of the Gross Theory of Betamore » Decay. The integrated beta strengths are instead found to be consistent with shell model predictions where the single-particle beta strengths are divided amoung many low-lying levels. The experimental beta strengths determined here have been used calculate the half-lives of 143 neutron deficient nuclei with Z=51–64 to a precision of 20% with respect to the measured values.« less

Calculations of long-range three-body interactions for He(n0λS )-He(n0λS )-He(n0'λL )

NASA Astrophysics Data System (ADS)

Yan, Pei-Gen; Tang, Li-Yan; Yan, Zong-Chao; Babb, James F.

2018-04-01

We theoretically investigate long-range interactions between an excited L -state He atom and two identical S -state He atoms for the cases of the three atoms all in spin-singlet states or all in spin-triplet states, denoted by He(n0λS )-He(n0λS )-He(n0'λL ), with n0 and n0' principal quantum numbers, λ =1 or 3 the spin multiplicity, and L the orbital angular momentum of a He atom. Using degenerate perturbation theory for the energies up to second-order, we evaluate the coefficients C3 of the first-order dipolar interactions and the coefficients C6 and C8 of the second-order additive and nonadditive interactions. Both the dipolar and dispersion interaction coefficients, for these three-body degenerate systems, show dependences on the geometrical configurations of the three atoms. The nonadditive interactions start to appear in second-order. To demonstrate the results and for applications, the obtained coefficients Cn are evaluated with highly accurate variationally generated nonrelativistic wave functions in Hylleraas coordinates for He(1 1S ) -He(1 1S ) -He(2 1S ) , He(1 1S ) -He(1 1S ) -He(2 1P ) , He(2 1S ) -He(2 1S ) -He(2 1P ) , and He(2 3S ) -He(2 3S ) -He(2 3P ) . The calculations are given for three like nuclei for the cases of hypothetical infinite mass He nuclei, and of real finite mass 4He or 3He nuclei. The special cases of the three atoms in equilateral triangle configurations are explored in detail, and for the cases in which one of the atoms is in a P state, we also present results for the atoms in an isosceles right triangle configuration or in an equally spaced collinear configuration. The results can be applied to construct potential energy surfaces for three helium atom systems.

Effective field theory for deformed atomic nuclei

DOE PAGES

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.

The abundances of solar accelerated nuclei from carbon to iron.

NASA Technical Reports Server (NTRS)

Mogro-Campero, A.; Simpson, J. A.

1972-01-01

Revised observation periods and new data are found to confirm previous evidence that the overabundance of solar-flare nuclei with respect to solar photospheric and coronal abundances increases with increasing atomic number. It is also verified that enhancements can vary from flare to flare and that this variability is large enough to explain the differences observed by various investigators regarding the magnitude of solar-flare high-Z particle enhancements. Additional evidence for a two-stage solar acceleration mechanism is obtained. It is shown that the galactic cosmic-ray source composition displays a similar overabundance as a function of atomic number.

Scissors mode of Gd nuclei studied from resonance neutron capture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kroll, J.; Baramsai, B.; Becker, J. A.

2012-10-20

Spectra of {gamma} rays following the neutron capture at isolated resonances of stable Gd nuclei were measured. The objectives were to get new information on photon strength of {sup 153,155-159}Gd with emphasis on the role of the M1 scissors-mode vibration. An analysis of the data obtained clearly indicates that the scissors mode is coupled not only to the ground state, but also to all excited levels of the nuclei studied. The specificity of our approach ensures unbiasedness in estimating the sumed scissors-mode strength {Sigma}B(M1){up_arrow}, even for odd product nuclei, for which conventional nuclear resonance fluorescence measurements yield only limited information.more » Our analysis indicates that for these nuclei the sum {Sigma}B(M1){up_arrow} increases with A and for {sup 157,159}Gd it is significantly higher compared to {sup 156,158}Gd.« less

Mass Independent Fractionation of Cadmium Isotopes During Thermal Ionization

NASA Astrophysics Data System (ADS)

Abouchami, W.; Galer, S. J.; Feldmann, H.; Schmitt, A. D.

2008-12-01

We have previously reported that Cd isotopes exhibit anomalous, non-mass dependent fractionation of odd versus even isotopes when measured by TIMS using silica gel-phosphoric acid activator. The deviation from mass dependent fractionation (MDF) on the odd masses 111 and 113 varies by fractions of a per-cent between runs. The effects cannot be explained by isobaric interferences, but seem, instead, to reflect mass independent fractionation (MIF) of Cd isotopes, much like that recently documented for Hg isotopes in natural systems (Bergquist and Blum, 2007). The absence of comparable Cd isotope anomalies in the ICP torch, and during extreme in-vacuo volatilization of Cd metal (Wombacher et al., 2004) conclusively implicates the silica gel activator in the process. So far, MIF has been documented for Cd, Zn and Pb isotopes when measured using the silica gel technique (Thirlwall, 2000; Schmitt et al., 2006; Manhes and Göpel, 2007). These MIF effects on Cd isotopes might perhaps be related to the non-mass dependence of nuclear volume with mass number, as described by Bigeleisen (1996) - also known as the "nuclear field shift". The MIF caused by the nuclear field shift results is a departure from MDF broadly characterized by a odd-even staggering with mass number. These effects have been quantified by Schauble (2007) who showed that the magnitude of the non-mass dependence for Hg and Tl isotopes lies in the ppm range for some simple reactions. Such MIF effects would appear, overall, far too small to account for our data, which require MIF offsets on the odd masses 111 and 113 approaching a per-cent. Moreover, an in-depth examination along the lines of Fujii et al. (2006) predicts tell-tale offsets for the even-even isotope pairs 114Cd/112Cd and 116Cd/112Cd as well, based upon the theory and the respective nuclear radii, but such accompanying offsets are unequivocally absent in our data. The odd-even isotope effects seen in our runs using silica gel activator are better explained by appealing to the nuclear spin (and magnetic moment) of odd nuclei alone. The "magnetic isotope effect" is a consequence of hyperfine coupling, in which an electron interacts with a nucleus of non-zero magnetic moment - i.e. one that has an odd number of nucleons (Turro, 1983; Buchachenko, 1995, 2001). This is purely a kinetic phenomenon in which the life-time, and thus the outcome, of reaction transition states is altered by the hyperfine splitting present in atoms with odd nuclei. The mechanism by which silica gel activator enhances the thermal ionization of elements such as Cd, Pb and Zn has been outlined by Kessinger and Delmore (2002). The first step involves the in-situ reduction of Cd2+ ions to Cd metal in the molten silica gel-phosphoric acid glass. It is most likely in this step - whereby two electrons are added - that a suitably long-lived transition state exists, during which the magnetic isotope effect enhances (or inhibits) reduction of masses 111 and 113 to metal species compared to those of even isotopes of Cd. The resulting "odd" and "even" populations of Cd-metal in the molten silica gel then cannot be related simply in terms of MDF. Overall, the magnetic isotope effect provides the best explanation of the MIF effects observed for Pb, Cd and Zn during thermal ionization with silica gel activator, and, probably, why the measured fractionation is always biased towards light isotopes.

Process-Structure-Property Relationships of Micron Thick Gadolinium Oxide Films Deposited by Reactive Electron Beam-Physical Vapor Deposition (EB-PVD)

DTIC Science & Technology

2014-12-01

surface roughness on film properties must be considered. Stability at the interface between the film and the substrate becomes critical with...etc.). Addition of atoms to the growing surface creates additional surface energy. Therefore, nuclei of a critical size 23 must be formed in order... critical nuclei size and a lower nucleation rate. Higher deposition rates result in a decreased critical nuclei size which leads to an increase in

In situ mechanical characterization of the cell nucleus by atomic force microscopy.

PubMed

Liu, Haijiao; Wen, Jun; Xiao, Yun; Liu, Jun; Hopyan, Sevan; Radisic, Milica; Simmons, Craig A; Sun, Yu

2014-04-22

The study of nuclear mechanical properties can provide insights into nuclear dynamics and its role in cellular mechanotransduction. While several methods have been developed to characterize nuclear mechanical properties, direct intracellular probing of the nucleus in situ is challenging. Here, a modified AFM (atomic force microscopy) needle penetration technique is demonstrated to mechanically characterize cell nuclei in situ. Cytoplasmic and nuclear stiffness were determined based on two different segments on the AFM indentation curves and were correlated with simultaneous confocal Z-stack microscopy reconstructions. On the basis of direct intracellular measurement, we show that the isolated nuclei from fibroblast-like cells exhibited significantly lower Young's moduli than intact nuclei in situ. We also show that there is in situ nucleus softening in the highly metastatic bladder cancer cell line T24 when compared to its less metastatic counterpart RT4. This technique has potential to become a reliable quantitative measurement tool for intracellular mechanics studies.

Dipole response of the odd-proton nucleus 205Tl up to the neutron-separation energy

DOE PAGES

Benouaret, N.; Beller, J.; Pai, H.; ...

2016-10-17

The low-lying electromagnetic dipole strength of the odd-proton nuclide 205Tl has been investigated up to the neutron separation energy exploiting the method of nuclear resonance fluorescence. In total, 61 levels of 205Tl have been identified. Lastly, the measured strength distribution of 205Tl were discussed and compared to those of even–even and even–odd mass nuclei in the same mass region as well as to calculations that have been performed within the quasi-particle phonon model.

Even-odd alternation of near-infrared spectra of alkane-α,ω-diols in their solid states

NASA Astrophysics Data System (ADS)

Toyama, Yuta; Murakami, Kohei; Yoshimura, Norio; Takayanagi, Masao

2018-05-01

Even-odd alternation of the melting points of α,ω-disubstituted linear alkanes such as alkane-α,ω-diols, alkane-α,ω-dinitriles and α,ω-diaminoalkanes is well known. Melting points for compounds with an even number of carbons in their alkyl chains are systematically higher than those for compounds with an odd number of carbons. In order to clarify the origin of this alternation, near-infrared absorption spectra of linear alkane-α,ω-diols with 3 to 9 carbon atoms in their alkyl chains were measured in the liquid and solid states. The band due to the first overtone of the Osbnd H stretching mode was investigated. The temperature-dependent spectra of all alkane-α,ω-diols in their liquid states were found to be similar; no even-odd alternation was observed. In the solid state, however, spectra of alkane-α,ω-diols with even and odd numbers of carbon atoms differed greatly. Spectra of alkane-α,ω-diols with an odd number of carbon atoms in their solid states were similar to those in the liquid states, although the variation of spectra observed upon lowering the temperature of liquid seemed to continue when the liquids were frozen. In contrast, spectra of alkane-α,ω-diols with an even number of carbon atoms in their liquid and solid states were found to be quite different. New bands appeared upon freezing. The observed even-odd alternation of the spectra observed for alkane-α,ω-diols in their solid states is presumably caused by their even-odd alternation of crystal structures.

Delayed fission of atomic nuclei (To the 50th anniversary of the discovery)

NASA Astrophysics Data System (ADS)

Skobelev, N. K.

2017-09-01

The history of the discovery of delayed nuclear fission is presented, and the retrospective of investigations into this phenomenon that were performed at various research centers worldwide is outlined. The results obtained by measuring basic delayed-fission features, including the fission probability, the total kinetic energy of fission fragments, and their mass distributions, are analyzed. Recommendations concerning further studies in various regions of nuclear map with the aim of searches for and investigation of atomic nuclei undergoing delayed fission are given. Lines of further research into features of delayed fission with the aim of solving current problems of fission physics are discussed.

Fusion barrier characteristics of actinides

NASA Astrophysics Data System (ADS)

Manjunatha, H. C.; Sridhar, K. N.

2018-03-01

We have studied fusion barrier characteristics of actinide compound nuclei with atomic number range 89 ≤ Z ≤ 103 for all projectile target combinations. After the calculation of fusion barrier heights and positions, we have searched for their parameterization. We have achieved the empirical formula for fusion barrier heights (VB), positions (RB), curvature of the inverted parabola (ħω) of actinide compound nuclei with atomic number range 89 ≤ Z ≤ 103 for all projectile target combinations (6

Isomorphic Properties of Atoms, Molecules, Water, DNA, Crystals, Earth, SolarSystem and Galaxies

NASA Astrophysics Data System (ADS)

Gareev, F. A.; Gareeva, G. F.; Zhidkova, I. E.

2009-03-01

We discuss the cooperative resonance synchronization enhancement mechanisms of Low Energy Nuclear Reactions (LENR). Some of the low energy external fields can be used as triggers for starting and enhancing exothermic LENR. Any external field shortening distances between protons in nuclei and electrons in atoms should enhance beta-decay (capture) or double-beta decay (capture). We have proposed a new mechanism of LENR: cooperative resonance synchronization processes in the whole system nuclei+atoms+condensed matter+gaseuos+plasma medium, which we suggest can occur at a smaller threshold than the corresponding ones on free constituents. The cooperative processes can be induced and enhanced by low energy external fields. The excess heat is the emission of internal energy, and transmutations at LENR are the result of redistribution inner energy of the whole system.

Study of crystallization mechanisms of Fe nanoparticle

NASA Astrophysics Data System (ADS)

Kien, P. H.; Trang, G. T. T.; Hung, P. K.

2017-06-01

In this paper, the nanoparticle (NP) Fe was investigated by means of molecular dynamics simulation. The crystallization mechanism was studied through the time evolution of crystal cluster and potential energies of different atom types. The simulation shows that the NP was crystallized into bcc crystal structure when it was annealed at 900 K for long times. At early stage of the annealing, small nuclei form in different places of NP and dissolve for short times. After long times some nuclei form and gather nearby which create the stable clusters in the core of NP. After that the crystal clusters grow in the direction to cover the core and then to spread into the surface of NP. Analyzing the energies of different type atoms, we found that the crystal growth is originated from specific atomic arrangement in the boundary region of crystal clusters.

Nuclear Data Sheets for A = 251–259 (odd)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Browne, E.; Tuli, J.K.

The evaluators present in this publication spectroscopic data and level schemes from radioactive decay and nuclear reaction studies for all known nuclei with mass numbers A = 251, 253, 255, 257, and 259.

Synthesis reactions and radioactive properties of transactinoid elements

NASA Astrophysics Data System (ADS)

Oganessian, Yu. Ts.

1994-10-01

It is well known that the heaviest elements of the periodic table have been synthesized in the cold fusion of magic nuclei of Pb with Z less than 26 ions. Because of dynamic limitations for fusion under strong Coulomb interaction of nuclei, the cross-sections of cold fusion reactions diminish exponentially with growing compound nucleus atomic number. For element Z = 110 produced in the reaction Pb-208(Ni-62,n)(sub 271)110, the expected cross-section is 10(exp -36) sq cm. In still more asymmetric reactions, when isotopes of actinoid elements irradiated with relatively light ions (Z less than or equal 12) are used as the target material, the compound nuclei possess an excitation energy of approx. 50 MeV. At this energy the nuclear shell effects are strongly suppressed and, as a result, in the case of hot compound nuclei of transactinoid elements the fission barrier is practically absent. The transition of these nuclei into the ground state depends strongly on the dynamic properties of the system with respect to the fission degree of freedom. Experimental studies were going on in two directions: (1) determination of the fission time by measuring the prefission neutrons (of Cf-Fm nuclei) in a wide interval of excitation energies; (2) direct synthesis of known nuclides with Z = 102-105 in reactions with ions of Ne-22, Mg-26, Al-27 and P-31 when final nuclei are produced in the ground state after the evaporation of five or six neutrons from the excited compound nuclei (E(sub x) = 50-60 MeV). The dependence of the reaction cross-section (HI, 5-6n) on the atomic number of the compound nucleus in different target-ion combinations points to the possibility of synthesizing new elements in hot fusion reactions. The advantage of these reactions arises from the use of neutron-rich nuclei like Cm-248 and Cf-249 which allows us to synthesize nuclei close to the deformed shell N = 162, for which a considerable growth of stability against spontaneous fission is predicted. Experimental set-ups and methods of detecting rare events of formation and decay of transactinide nuclei are described.

Learning Nuclear Science with Marbles

ERIC Educational Resources Information Center

Constan, Zach

2010-01-01

Nuclei are "small": if an atom was the size of a football field, the nucleus would be an apple sitting on the 50-yd line. At the same time, nuclei are "dense": the Earth, compressed to nuclear density, could fit inside four Sears Towers. The subatomic level is strange and exotic. For that reason, it's not hard to get young minds excited about…

The project of the mass separator of atomic nuclei produced in heavy ion induced reactions

NASA Astrophysics Data System (ADS)

Oganessian, Yu. Ts.; Shchepunov, V. A.; Dmitriev, S. N.; Itkis, M. G.; Gulbekyan, G. G.; Khabarov, M. V.; Bekhterev, V. V.; Bogomolov, S. L.; Efremov, A. A.; Pashenko, S. V.; Stepantsov, S. V.; Yeremin, A. V.; Yavor, M. I.; Kalimov, A. G.

2003-05-01

A new separator and mass analyzer, named MASHA (mass analyzer of super heavy atoms), has been designed at the Flerov Laboratory JINR Dubna to separate and measure masses of nuclei and molecules with precision better than 10 -3. The set up can work in the wide mass range from A≈20 to A≈500, its mass acceptance is as large as ±2.8%. In particular, it allows unambiguous mass identification of super heavy nuclei with a resolution better than 1 amu at the level of 300 amu. Synthesized in nuclear reactions nuclides are emitted from an ECR ion source at energy E=40 kV and charge state Q=+1. Then they pass the following steps of separation and analysis: the first section of rough separation, the second section of separation and mass analysis and the final section of separation with a 90° electrostatic deflector. In the focal plane of the device, a focal plane detector determines positions (masses) of studied nuclei. Ion optics of the analyzer, optimized up to the second order, is considered. Description of its elements and subsystems is given.

Extension of the nuclear mass surface for neutron-rich isotopes of argon through iron

NASA Astrophysics Data System (ADS)

Meisel, Zachary Paul

Nuclear mass measurement has maintained an important position in the field of nuclear physics for a little over a century. Nuclear masses provide key evidence of the structural transformation of nuclei away from the valley of beta-stability and are essential input for many simulations of extreme astrophysical environments. However, obtaining these masses is often a challenging endeavor due to the low production cross sections and short half-lives of the exotic nuclei which are of particular interest. To this end, the time-of-flight mass measurement technique has been developed to obtain the masses of several nuclei at once to precisions of 1 part in 105 with virtually no half-life limitation. This dissertation contains a description of the experiment, analysis, and results of the second implementation of the time-of-flight nuclear mass measurement technique at the National Superconducting Cyclotron Laboratory. 18 masses were obtained for neutron-rich isotopes of argon through iron, where the masses of 48Ar, 49Ar, 56Sc, 57Sc, 64Cr, 67Mn, and 69Fe were measured for the first time. These newly obtained masses were applied to outstanding problems in nuclear structure and nuclear astrophysics, resulting in significant scientific advances. The measurement results for 48Ar and 49Ar, which were found to have atomic mass excesses of -22.28(31) MeV and -17.8(1.1) MeV, respectively, provide strong evidence for the closed shell nature of neutron number N = 28 in argon. It follows that argon is therefore the lowest even-Z element exhibiting the N = 28 closed shell. The masses of 64Cr, 67 Mn, and 69Fe, which were found to have atomic mass excesses of -33.48(44) MeV, -34.09(62) MeV, and -39.35(60) MeV, respectively, show signs of nuclear deformation occurring around the N = 40 subshell. In addition, we found 64Cr is substantially less bound than predicted by global mass models that are commonly used in nuclear astrophysics simulations, resulting in a significant reduction in the predicted strength and depth of electron capture heating in the accreted neutron star crust due to the rather abundant A = 64 mass-chain. The reported value for the atomic mass excess of 56Sc, -24.85(59)(+0,-54) MeV, which contains an asymmetric systematic uncertainty due to potential isomeric contamination, results in a smaller than expected odd-even mass staggering in the A = 56 mass chain. Depending on the choice of theoretical models for electron capture transition strengths and energies, this could lead to strong Urca cooling in accreted neutron star crusts, due to the large amount of A = 56 material predicted to be present on the surface of accreted neutron stars.

Even-odd alternation of near-infrared spectra of alkane-α,ω-diols in their solid states.

PubMed

Toyama, Yuta; Murakami, Kohei; Yoshimura, Norio; Takayanagi, Masao

2018-05-15

Even-odd alternation of the melting points of α,ω-disubstituted linear alkanes such as alkane-α,ω-diols, alkane-α,ω-dinitriles and α,ω-diaminoalkanes is well known. Melting points for compounds with an even number of carbons in their alkyl chains are systematically higher than those for compounds with an odd number of carbons. In order to clarify the origin of this alternation, near-infrared absorption spectra of linear alkane-α,ω-diols with 3 to 9 carbon atoms in their alkyl chains were measured in the liquid and solid states. The band due to the first overtone of the OH stretching mode was investigated. The temperature-dependent spectra of all alkane-α,ω-diols in their liquid states were found to be similar; no even-odd alternation was observed. In the solid state, however, spectra of alkane-α,ω-diols with even and odd numbers of carbon atoms differed greatly. Spectra of alkane-α,ω-diols with an odd number of carbon atoms in their solid states were similar to those in the liquid states, although the variation of spectra observed upon lowering the temperature of liquid seemed to continue when the liquids were frozen. In contrast, spectra of alkane-α,ω-diols with an even number of carbon atoms in their liquid and solid states were found to be quite different. New bands appeared upon freezing. The observed even-odd alternation of the spectra observed for alkane-α,ω-diols in their solid states is presumably caused by their even-odd alternation of crystal structures. Copyright © 2018 Elsevier B.V. All rights reserved.

Realistic Gamow shell model for resonance and continuum in atomic nuclei

NASA Astrophysics Data System (ADS)

Xu, F. R.; Sun, Z. H.; Wu, Q.; Hu, B. S.; Dai, S. J.

2018-02-01

The Gamow shell model can describe resonance and continuum for atomic nuclei. The model is established in the complex-moment (complex-k) plane of the Berggren coordinates in which bound, resonant and continuum states are treated on equal footing self-consistently. In the present work, the realistic nuclear force, CD Bonn, has been used. We have developed the full \\hat{Q}-box folded-diagram method to derive the realistic effective interaction in the model space which is nondegenerate and contains resonance and continuum channels. The CD-Bonn potential is renormalized using the V low-k method. With choosing 16O as the inert core, we have applied the Gamow shell model to oxygen isotopes.

The decay of hot nuclei formed in La-induced reactions at E/A=45 MeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Libby, Bruce

1993-01-01

The decay of hot nuclei formed in the reactions 139La + 27Al, 51V, natCu, and 139La were studied by the coincident detection of up to four complex fragments (Z > 3) emitted in these reactions. Fragments were characterized as to their atomic number, energy and in- and out-of-plane angles. The probability of the decay by an event of a given complex fragment multiplicity as a function of excitation energy per nucleon of the source is nearly independent of the system studied. Additionally, there is no large increase in the proportion of multiple fragment events as the excitation energy of themore » source increases past 5 MeV/nucleon. This is at odds with many prompt multifragmentation models of nuclear decay. The reactions 139La + 27Al, 51V, natCu were also studied by combining a dynamical model calculation that simulates the early stages of nuclear reactions with a statistical model calculation for the latter stages of the reactions. For the reaction 139La + 27Al, these calculations reproduced many of the experimental features, but other features were not reproduced. For the reaction 139La + 51V, the calculation failed to reproduce somewhat more of the experimental features. The calculation failed to reproduce any of the experimental features of the reaction 139La + natCu, with the exception of the source velocity distributions.« less

The decay of hot nuclei formed in La-induced reactions at E/A=45 MeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Libby, B.

1993-01-01

The decay of hot nuclei formed in the reactions [sup 139]La + [sup 27]Al, [sup 51]V, [sup nat]Cu, and [sup 139]La were studied by the coincident detection of up to four complex fragments (Z > 3) emitted in these reactions. Fragments were characterized as to their atomic number, energy and in- and out-of-plane angles. The probability of the decay by an event of a given complex fragment multiplicity as a function of excitation energy per nucleon of the source is nearly independent of the system studied. Additionally, there is no large increase in the proportion of multiple fragment events asmore » the excitation energy of the source increases past 5 MeV/nucleon. This is at odds with many prompt multifragmentation models of nuclear decay. The reactions [sup 139]La + [sup 27]Al, [sup 51]V, [sup nat]Cu were also studied by combining a dynamical model calculation that simulates the early stages of nuclear reactions with a statistical model calculation for the latter stages of the reactions. For the reaction [sup 139]La + [sup 27]Al, these calculations reproduced many of the experimental features, but other features were not reproduced. For the reaction [sup 139]La + [sup 51]V, the calculation failed to reproduce somewhat more of the experimental features. The calculation failed to reproduce any of the experimental features of the reaction [sup 139]La + [sup nat]Cu, with the exception of the source velocity distributions.« less

Theoretical and experimental α decay half-lives of the heaviest odd-Z elements and general predictions

NASA Astrophysics Data System (ADS)

Zhang, H. F.; Royer, G.

2007-10-01

Theoretical α decay half-lives of the heaviest odd-Z nuclei are calculated using the experimental Qα value. The barriers in the quasimolecular shape path are determined within a Generalized Liquid Drop Model (GLDM) and the WKB approximation is used. The results are compared with calculations using the Density-Dependent M3Y (DDM3Y) effective interaction and the Viola-Seaborg-Sobiczewski (VSS) formulas. The calculations provide consistent estimates for the half-lives of the α decay chains of these superheavy elements. The experimental data stand between the GLDM calculations and VSS ones in the most time. Predictions are provided for the α decay half-lives of other superheavy nuclei within the GLDM and VSS approaches using the recent extrapolated Qα of Audi, Wapstra, and Thibault [Nucl. Phys. A729, 337 (2003)], which may be used for future experimental assignment and identification.

The P-factor and atomic mass systematics: Application to medium mass nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brenner, D.S.; Haustein, P.E.; Casten, R.F.

1988-01-01

The P formalism was applied to atomic mass systematics for medium and heavy nuclei. The P-factor linearizes the structure-dependent part of the nuclear mass in those regions which are free from subshell effects indicating that the attractive quadrupole p-n force plays an important role in determining the binding of valence nucleons. Where marked non-linearities occur, the P-factor provides a means for recognizing subshell closures and/or other structural features not embodied in the simple assumptions of abrupt shell or subshell changes. These are thought to be regions where the monopole part of the p-n interaction is highly orbit dependent and altersmore » the underlying single-particle structure as a function of A, N or Z. Finally, in those regions where the systematics are smooth and subshells are absent, the P-factor provides a means for predicting masses of some nuclei far-from-stability by interpolation rather than by extrapolation. 5 figs.« less

Muon, photon and nuclear CERs for ββ - ν response studies

NASA Astrophysics Data System (ADS)

Ejiri, H.

2015-10-01

Neutrino nuclear responses for neutrino-less double beta decays (0νββ DBD) are studied by muon, photon and nuclear charge exchange reactions (CER) and β-EC transitions. These experimental responses with low and medium momentum transfers are used to evaluate 0νββ nuclear matrix elements and the solar neutrino interactions with atoms and nuclei of DBD detectors. Gamma-ray measurements from residual RI nuclei produced by (µ, νµxn) reactions on 100Mo shows a giant resonance around 12-15 MeV for µ- capture strength. Single β Gamow-Teller (GT) and spin-dipole (SD) strengths are reduced with respect to pnQRPA calculations by gAe f f≈0.5 -0.6 gA , suggesting considerable reductions of the axial vector responses for DBD. Solar neutrino nuclear interactions with nuclei of the DBD isotopes and atoms of liquid scintillators used for DBD experiments are shown to be the serious backgrounds at the ROI (region of interest) of 0νββ.

Can even-order laser harmonics exhibited by Bohmian trajectories in symmetric potentials be observed?

PubMed

Peatross, J; Johansen, J

2014-01-13

Strong-field laser-atom interactions provide extreme conditions that may be useful for investigating the de Broglie-Bohm quantum interpretation. Bohmian trajectories representing bound electrons in individual atoms exhibit both even and odd harmonic motion when subjected to a strong external laser field. The phases of the even harmonics depend on the random initial positions of the trajectories within the wave function, making the even harmonics incoherent. In contrast, the phases of odd harmonics remain for the most part coherent regardless of initial position. Under the conjecture that a Bohmian point particle plays the role of emitter, this suggests an experiment to determine whether both even and odd harmonics are produced at the atomic level. Estimates suggest that incoherent emission of even harmonics may be detectable out the side of an intense laser focus interacting with a large number of atoms.

Enrichment of heavy nuclei in He-3-rich flares. [Imp-7 observed solar events

NASA Technical Reports Server (NTRS)

Hurford, G. J.; Mewaldt, R. A.; Stone, E. C.; Vogt, R. E.

1975-01-01

IMP-7 observations of five solar-flare particle events characterized by He-3 enrichment are reported which show that such events are also enriched in nuclei with charges (Z) of at least 6. The ratio of these nuclei to H-1 at approximately 3 MeV/nucleon was found to be enriched by about 10 to 100 times, while the ratio with respect to He-4 was enriched by about 3 to 30 times. It is suggested that the simultaneous enhancement of He-3 and the heavier nuclei as well as the absence of H-2 and H-3 during the observed events may be partly due to a preferential acceleration process which depends on the ratio of the square of the charge to the atomic weight of the nuclei.

High baryon densities in heavy ion collisions at energies attainable at the BNL Relativistic Heavy-Ion Collider and the CERN Large Hadron Collider

NASA Astrophysics Data System (ADS)

Li, Ming; Kapusta, Joseph I.

2017-01-01

In very high-energy collisions nuclei are practically transparent to each other but produce very hot nearly baryon-free matter in the so-called central rapidity region. The energy in the central rapidity region comes from the kinetic energy of the colliding nuclei. We calculate the energy and rapidity loss of the nuclei using the color glass condensate model. This model also predicts the excitation energy of the nuclear fragments. Using a space-time picture of the collision we calculate the baryon and energy densities of the receding baryonic fireballs. For central collisions of gold nuclei at the highest energy attainable at the Relativistic Heavy-Ion Collider, for example, we find baryon densities more than ten times that of atomic nuclei over a large volume.

New model of the average neutron and proton pairing gaps

NASA Astrophysics Data System (ADS)

Madland, David G.; Nix, J. Rayford

1988-01-01

By use of the BCS approximation applied to a distribution of dense, equally spaced levels, we derive new expressions for the average neutron pairing gap ¯gD n and average proton pairing gap ¯gD p. These expressions, which contain exponential terms, take into account the dependencies of ¯gD n and ¯gD p upon both the relative neutron excess and shape of the nucleus. The three constants that appear are determined by a least-squares adjustment to experimental pairing gaps obtained by use of fourth-order differences of measured masses. For this purpose we use the 1986 Audi-Wapstra mid-stream mass evaluation and take into account experimental uncertainties. Our new model explains not only the dependencies of ¯gD n and ¯gD p upon relative neutron excess and nuclear shape, but also the experimental result that for medium and heavy nuclei ¯gD n is generally smaller than ¯gD p. We also introduce a new expression for the average residual neutron-proton interaction energy ¯gd that appears in the masses of odd-odd nuclei, and determine the constant that appears by an analogous least-squares adjustment to experimental mass differences. Our new expressions for ¯gD n, ¯gD p and ¯gd should permit extrapolation of these quantities to heavier nuclei and to nuclei farther removed from the valley of β stability than do previous parameterizations.

Structural and compositional evolution of Al{sub 3}(Zr,Y) precipitates in Al-Zr-Y alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Haiyan, E-mail: gaohaiyan@sjtu.edu.cn

Structural and compositional evolution of Al{sub 3}(Zr,Y) precipitates in aged Al-Zr-Y alloy was investigated through atom probe tomography (APT) and transmission electron microscope (TEM) analysis and first principles calculations. The results show that short-bar-shaped D0{sub 19}-Al{sub 3}Y with some Zr atoms dissolved in precipitated at the very beginning of decomposition and worked as heterogeneous nuclei for L1{sub 2}-Al{sub 3}Zr with spherical morphology after being aged at 400 °C for 2 h. Quasi-static coarsening happened as the aging treatment lasted from 2 h to 200 h. However, distribution of Zr and Y atoms in Al{sub 3}(Zr,Y) is nearly uniform and Al{submore » 3}(Zr,Y) do not have the typical “Al{sub 3}RE core-Al{sub 3}Zr shell” structure which observed in other RE containing Al-Zr-RE alloys with L1{sub 2}-Al{sub 3}RE as nuclei. First principles calculations revealed that binding energy between Y and Zr is strong during the growth of Al{sub 3}(Zr,Y), which led to the co-precipitation of Y and Zr atoms and attribute to the evolution of Al{sub 3}(Zr,Y). - Highlights: •Al{sub 3}Y precipitated firstly and then became nuclei for Al{sub 3}Zr during aging of Al-Zr-Y. •Al{sub 3}(Zr,Y) precipitates do not have the typical “Al{sub 3}Y core-Al{sub 3}Zr shell” structure. •Strong binding between Y and Zr led to the co-precipitation of Y and Zr atoms.« less

Quadrupole and octupole shapes in nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cline, D.

1993-12-31

The heavy-ion multiple Coulomb excitation technique, which has benefited from many important contributions by Dick Diamond, has developed to the stage where rather complete sets of E1, E2 and E3 matrix elements are being measured. These provide a sensitive measures of quadrupole and octupole deformation in nuclei. The completeness of the E2 data is sufficient to determine directly the centroids and fluctuation widths of the E2 properties in the principal axis frame for low-lying states. The results and model implications of recent Coulomb excitation measurements of the quadrupole shapes in odd and even A nuclei will be presented. Recent measurementsmore » of E1, E2 and E3 matrix elements for collective bands in N=88 and Z=88 nuclei show that octupole correlations play an important role. These results and the implications regarding octupole deformation and reflection asymmetry will be discussed.« less

Definition of molecular structure: by choice or by appeal to observation?

PubMed

Bader, Richard F W

2010-07-22

There are two schools of thought in chemistry: one derived from the valence bond and molecular orbital models of bonding, the other appealing directly to the measurable electron density and the quantum mechanical theorems that determine its behavior, an approach embodied in the quantum theory of atoms in molecules, QTAIM. No one questions the validity of the former approach, and indeed molecular orbital models and QTAIM play complementary roles, the models finding expression in the principles of physics. However, some orbital proponents step beyond the models to impose their personal stamp on their use in interpretive chemistry, by denying the possible existence of a physical basis for the concepts of chemistry. This places them at odds with QTAIM, whose very existence stems from the discovery in the observable topology of the electron density, the definitions of atoms, of the bonding between atoms and hence of molecular structure. Relating these concepts to the electron density provides the necessary link for their ultimate quantum definition. This paper explores in depth the possible causes of the difficulties some have in accepting the quantum basis of structure beginning with the arguments associated with the acceptance of a "bond path" as a criterion for bonding. This identification is based on the finding that all classical structures may be mapped onto molecular graphs consisting of bond paths linking neighboring atoms, a mapping that has no known exceptions and one that is further bolstered by the finding that there are no examples of "missing bond paths". Difficulties arise when the quantum concept is applied to systems that are not amenable to the classical models of bonding. Thus one is faced with the recurring dilemma of science, of having to escape the constraints of a model that requires a change in the existing paradigm, a process that has been in operation since the discovery of new and novel structures necessitated the extension of the Lewis model and the octet rule. The paper reviews all facets of bonding beginning with the work of Pauling and Slater in their accounting for crystal structures, taking note of Pauling's advocating possible bonding between large anions. Many examples of nonbonded or van der Waals interactions are considered from both points of view. The final section deals with the consequences of the realization that bonded quantum atoms that share an interatomic surface do not "overlap". The time has come for entering students of chemistry to be taught that the electron density can be seen, touched, and measured and that the chemical structures they learn are in fact the tracings of "bonds" onto lines of maximum density that link bonded nuclei. Matter, as we perceive it, is bound by the electrostatic force of attraction between the nuclei and the electron density.

Multipolar electrostatics for proteins: atom-atom electrostatic energies in crambin.

PubMed

Yuan, Yongna; Mills, Matthew J L; Popelier, Paul L A

2014-02-15

Accurate electrostatics necessitates the use of multipole moments centered on nuclei or extra point charges centered away from the nuclei. Here, we follow the former alternative and investigate the convergence behavior of atom-atom electrostatic interactions in the pilot protein crambin. Amino acids are cut out from a Protein Data Bank structure of crambin, as single amino acids, di, or tripeptides, and are then capped with a peptide bond at each side. The atoms in the amino acids are defined through Quantum Chemical Topology (QCT) as finite volume electron density fragments. Atom-atom electrostatic energies are computed by means of a multipole expansion with regular spherical harmonics, up to a total interaction rank of L = ℓA+ ℓB + 1 = 10. The minimum internuclear distance in the convergent region of all the 15 possible types of atom-atom interactions in crambin that were calculated based on single amino acids are close to the values calculated from di and tripeptides. Values obtained at B3LYP/aug-cc-pVTZ and MP2/aug-cc-pVTZ levels are only slightly larger than those calculated at HF/6-31G(d,p) level. This convergence behavior is transferable to the well-known amyloid beta polypeptide Aβ1-42. Moreover, for a selected central atom, the influence of its neighbors on its multipole moments is investigated, and how far away this influence can be ignored is also determined. Finally, the convergence behavior of AMBER becomes closer to that of QCT with increasing internuclear distance. Copyright © 2013 Wiley Periodicals, Inc.

Improved limit on the Ra 225 electric dipole moment

DOE PAGES

Bishof, Michael; Parker, Richard H.; Bailey, Kevin G.; ...

2016-08-03

In this study, octupole-deformed nuclei, such as that of 225Ra, are expected to amplify observable atomic electric dipole moments (EDMs) that arise from time-reversal and parity-violating interactions in the nuclear medium. In 2015 we reported the first “proof-of-principle” measurement of the 225Ra atomic EDM.

Improved limit on the Ra 225 electric dipole moment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bishof, Michael; Parker, Richard H.; Bailey, Kevin G.

In this study, octupole-deformed nuclei, such as that of 225Ra, are expected to amplify observable atomic electric dipole moments (EDMs) that arise from time-reversal and parity-violating interactions in the nuclear medium. In 2015 we reported the first “proof-of-principle” measurement of the 225Ra atomic EDM.

E1 transitions from octupole vibration states

NASA Astrophysics Data System (ADS)

Cottle, P. D.

1993-04-01

Electric dipole moments are extracted from data for E1 transitions deexciting octupole vibration states in nineteen nuclei. The moments are then compared to values calculated using the droplet model prescription of Dorso, Myers, and Swiatecki. It is found that the E1 moments in quadrupole deformed nuclei can be reproduced with the droplet model using the same model parameters that reproduce atomic masses and fission barriers. This result supports the suggestion of Butler and Nazarewicz that single particle effects are usually much smaller than macroscopic effects in E1 transitions associated with octupole vibrations in reflection symmetric deformed nuclei.

Nucleon Isovector Pairing in Nuclei: Microscopic Approach, Boson Representation, and Collective Model

NASA Astrophysics Data System (ADS)

Jolos, R. V.; Kartavenko, V. G.; Kolganova, E. A.

2018-03-01

Nucleon pair correlations in atomic nuclei are analyzed within a nuclear microscopic model with residual isovector pairing forces. These are formulated in the boson representation of fermion operators whereby the collective mode of pair excitations can be isolated without restricting the size of the one-particle basis. This method allows one to analyze the fluctuations in the nonsuperfluid phase of nuclear matter, its phase transition to the superfluid phase, and strong pair correlations. The performance of the method is exemplified by numerical results for the nuclei in the vicinity of the doubly magic 56Ni nucleus.

Investigation of 14-15 MeV ( n, t) Reaction Cross-sections by Using New Evaluated Empirical and Semi-empirical Systematic Formulas

NASA Astrophysics Data System (ADS)

Tel, E.; Aydın, A.; Kaplan, A.; Şarer, B.

2008-09-01

In the hybrid reactor, tritium self-sufficiency must be maintained for a commercial power plant. For self-sustaining (D-T) fusion driver tritium breeding ratio should be greater than 1.05. Working out the systematics of ( n, t) reaction cross-sections are of great importance for the definition of the excitation function character for the given reaction taking place on various nuclei at energies up to 20 MeV. In this study we have investigated asymmetry term effect for the ( n, t) reaction cross-sections at 14-15 neutron incident energy. It has been discussed the odd-even effect and the pairing effect considering binding energy systematic of the nuclear shell model for the new experimental data and new cross-sections formulas ( n, t) reactions developed by Tel et al. We have determined a different parameter groups by the classification of nuclei into even-even, even-odd and odd-even for ( n, t) reactions cross-sections. The obtained empirical and semi-empirical formulas by fitting two parameter for ( n, t) reactions were given. All calculated results have been compared with the experimental data and the other semi-empirical formulas.

Effect of solar proton events in 1978 and 1979 on the odd nitrogen abundance in the middle atmosphere

NASA Technical Reports Server (NTRS)

Jackman, Charles H.; Meade, Paul E.

1988-01-01

Daily average solar proton flux data for 1978 and 1979 are used in a proton energy degradation scheme to derive ion pair production rates and atomic nitrogen production rates. The latter are computed in a form suitable for inclusion in an atmopheric, two-dimensional, time-dependent photochemical model. Odd nitrogen distributions are computed from the model, including atomic nitrogen production from solar protons, and are compared with baseline distributions. The comparisons show that the average effect of the solar protons in 1978 and 1979 was to cause changes in odd nitrogen only above 10 mbar and at latitudes only above about 50 deg in both hemispheres. The influence of the solar proton-produced odd nitrogen on the local abundance of odd nitrogen depends primarily on the background odd nitrogen abundance as well as the altitude and season.

Momentum sharing in imbalanced Fermi systems

NASA Astrophysics Data System (ADS)

Hen, O.; Sargsian, M.; Weinstein, L. B.; Piasetzky, E.; Hakobyan, H.; Higinbotham, D. W.; Braverman, M.; Brooks, W. K.; Gilad, S.; Adhikari, K. P.; Arrington, J.; Asryan, G.; Avakian, H.; Ball, J.; Baltzell, N. A.; Battaglieri, M.; Beck, A.; Beck, S. May-Tal; Bedlinskiy, I.; Bertozzi, W.; Biselli, A.; Burkert, V. D.; Cao, T.; Carman, D. S.; Celentano, A.; Chandavar, S.; Colaneri, L.; Cole, P. L.; Crede, V.; D'Angelo, A.; De Vita, R.; Deur, A.; Djalali, C.; Doughty, D.; Dugger, M.; Dupre, R.; Egiyan, H.; El Alaoui, A.; El Fassi, L.; Elouadrhiri, L.; Fedotov, G.; Fegan, S.; Forest, T.; Garillon, B.; Garcon, M.; Gevorgyan, N.; Ghandilyan, Y.; Gilfoyle, G. P.; Girod, F. X.; Goetz, J. T.; Gothe, R. W.; Griffioen, K. A.; Guidal, M.; Guo, L.; Hafidi, K.; Hanretty, C.; Hattawy, M.; Hicks, K.; Holtrop, M.; Hyde, C. E.; Ilieva, Y.; Ireland, D. G.; Ishkanov, B. I.; Isupov, E. L.; Jiang, H.; Jo, H. S.; Joo, K.; Keller, D.; Khandaker, M.; Kim, A.; Kim, W.; Klein, F. J.; Koirala, S.; Korover, I.; Kuhn, S. E.; Kubarovsky, V.; Lenisa, P.; Levine, W. I.; Livingston, K.; Lowry, M.; Lu, H. Y.; MacGregor, I. J. D.; Markov, N.; Mayer, M.; McKinnon, B.; Mineeva, T.; Mokeev, V.; Movsisyan, A.; Camacho, C. Munoz; Mustapha, B.; Nadel-Turonski, P.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Osipenko, M.; Pappalardo, L. L.; Paremuzyan, R.; Park, K.; Pasyuk, E.; Phelps, W.; Pisano, S.; Pogorelko, O.; Price, J. W.; Procureur, S.; Prok, Y.; Protopopescu, D.; Puckett, A. J. R.; Rimal, D.; Ripani, M.; Ritchie, B. G.; Rizzo, A.; Rosner, G.; Roy, P.; Rossi, P.; Sabatié, F.; Schott, D.; Schumacher, R. A.; Sharabian, Y. G.; Smith, G. D.; Shneor, R.; Sokhan, D.; Stepanyan, S. S.; Stepanyan, S.; Stoler, P.; Strauch, S.; Sytnik, V.; Taiuti, M.; Tkachenko, S.; Ungaro, M.; Vlassov, A. V.; Voutier, E.; Walford, N. K.; Wei, X.; Wood, M. H.; Wood, S. A.; Zachariou, N.; Zana, L.; Zhao, Z. W.; Zheng, X.; Zonta, I.; aff16

2014-10-01

The atomic nucleus is composed of two different kinds of fermions: protons and neutrons. If the protons and neutrons did not interact, the Pauli exclusion principle would force the majority of fermions (usually neutrons) to have a higher average momentum. Our high-energy electron-scattering measurements using 12C, 27Al, 56Fe, and 208Pb targets show that even in heavy, neutron-rich nuclei, short-range interactions between the fermions form correlated high-momentum neutron-proton pairs. Thus, in neutron-rich nuclei, protons have a greater probability than neutrons to have momentum greater than the Fermi momentum. This finding has implications ranging from nuclear few-body systems to neutron stars and may also be observable experimentally in two-spin-state, ultracold atomic gas systems.

Are there any narrow K--nuclear states?

NASA Astrophysics Data System (ADS)

Hrtánková, Jaroslava; Mareš, Jiří

2017-07-01

We performed self-consistent calculations of K--nuclear quasi-bound states using a single-nucleon K- optical potential derived from chiral meson-baryon coupled-channel interaction models, supplemented by a phenomenological K- multinucleon potential introduced recently to achieve good fits to kaonic atom data [1]. Our calculations show that the effect of K- multinucleon interactions on K- widths in nuclei is decisive. The resulting widths are considerably larger than corresponding binding energies. Moreover, when the density dependence of the K--multinucleon interactions derived in the fits of kaonic atoms is extended to the nuclear interior, the only two models acceptable after imposing as additional constraint the single-nucleon fraction of K- absorption at rest do not yield any kaonic nuclear bound state in majority of considered nuclei.

Constraints on Coulomb energy, neutron skin thickness in 208Pb, and symmetry energy

NASA Astrophysics Data System (ADS)

Dong, J. M.; Wang, L. J.; Zuo, W.; Gu, J. Z.

2018-03-01

The charge-symmetry-breaking (CSB) effect in a nuclear medium that gives rise to the first-order symmetry energy in finite nuclei is discussed in detail in the present paper. For heavy and superheavy nuclei with large neutron excesses, it should be nonnegligible in high-precision mass predictions, and importantly it affects the stability of these nuclei. Combined with this CSB effect, the Coulomb energy is constrained by using the experimental Coulomb displacement energy of mirror nuclei, and then the mass-dependent symmetry energy coefficients of heavy nuclei are reextracted with the experimental β--decay energies of heavy odd-A nuclei and with the experimental mass differences. Based on these results, we probe the neutron skin thickness Δ Rn p of 208Pb and the density-dependent symmetry energy coefficient of nuclear matter. Δ Rn p in 208Pb is found to be 0.158 ±0.014 fm , and the slopes L of the symmetry energy coefficient at densities of ρ =0.16 and ρ =0.11 fm-3 are estimated to be 42 ±8 and 42 ±3 MeV , respectively. These results would be meaningful to discriminate between the models and the predictions that are relevant for the investigations on properties of nuclei and of neutron stars.

Calculation of (P,T) -odd electric dipole moments for the diamagnetic atoms X129e , Y171b , H199g , R211n , and R225a

NASA Astrophysics Data System (ADS)

Dzuba, V. A.; Flambaum, V. V.; Porsev, S. G.

2009-09-01

Electric dipole moments of diamagnetic atoms of experimental interest are calculated using the relativistic Hartree-Fock and random-phase approximation methods, the many-body perturbation theory, and the configuration-interaction technique. We consider (P,T) -odd interactions, which give rise to atomic electric dipole moment in the second order of the perturbation theory. These include nuclear Schiff moment, (P,T) -odd electron-nucleon interaction, and electron electric dipole moment. Interpretation of an experimental constraint of a permanent electric dipole moment of H199g [W. C. Griffith, M. D. Swallows, T. H. Loftus, M. V. Romalis, B. R. Heckel, and E. N. Fortson, Phys. Rev. Lett. 102, 101601 (2009)] is discussed.

Odd nitrogen production by meteoroids

NASA Technical Reports Server (NTRS)

Park, C.; Menees, G. P.

1978-01-01

The process by which odd nitrogen species (atomic nitrogen and nitric oxide) are formed during atmospheric entry of meteoroids is analyzed theoretically. An ablating meteoroid is assumed to be a point source of mass with a continuum regime evolving in its wake. The amounts of odd nitrogen species, produced by high-temperature reactions of air in the continuum wake, are calculated by numerical integration of chemical rate equations. Flow properties are assumed to be uniform across the wake, and 29 reactions involving five neutral species and five singly ionized species are considered, as well as vibrational and electron temperature nonequilibrium phenomena. The results, when they are summed over the observed mass, velocity, and entry-angle distribution of meteoroids, provide odd-nitrogen-species annual global production rates as functions of altitude. The peak production of nitric oxide is found to occur at an altitude of about 85 km; atomic nitrogen production peaks at about 95 km. The total annual rate for nitric oxide is 40 million kg; for atomic nitrogen it is 170 million kg.

Length-dependent structural stability of linear monatomic Cu wires

NASA Astrophysics Data System (ADS)

Singh, Gurvinder; Kumar, Krishan; Singh, Baljinder; Moudgil, R. K.

2018-05-01

We present first-principle calculations based on density functional theory for the finite-length monatomic Cu atom linear wires. The structure and its stability with increasing wire length in terms of number of atoms (N) is determined. Interestingly, the bond length is found to exhibit an oscillatory structure (the so-called magic length phenomenon), with a qualitative change in oscillatory behavior as one moves from even N wire to odd N wire. The even N wires follow simple even-odd oscillations whereas odd N wires show a phase change at the half length of the wires. The stability of the wire structure, determined in terms of the wire formation energy, also contains even-odd oscillation as a function of wire length. However, the oscillations in formation energy reverse its phase after the wire length is increased beyond N=12. Our findings are seen to be qualitatively consistent with recent simulations for a similar class finite-length metal atom wires.

Excitation of Nuclei and Atoms Trapping in Optical Fields of High Intensity

DTIC Science & Technology

2006-11-01

the new relativistic wave equation for half- spin particle interacting with the electromagnetic field. The proposed equation is Lorentz and gauge ...CONTENTS Task 1. Gamma-ray laser with hidden inversion of nuclear state populations 3 Introduction 3 Recoil-accompanied nuclear...31 Task 2. Extended ensemble of monoenergetic atoms 33 Introduction 33 Results 37 Conclusion 66

Magnesium and Calcium in Isolated Cell Nuclei

PubMed Central

Naora, H.; Naora, H.; Mirsky, A. E.; Allfrey, V. G.

1961-01-01

The calcium and magnesium contents of thymus nuclei have been determined and the nuclear sites of attachment of these two elements have been studied. The nuclei used for these purposes were isolated in non-aqueous media and in sucrose solutions. Non-aqueous nuclei contain 0.024 per cent calcium and 0.115 per cent magnesium. Calcium and magnesium are held at different sites. The greater part of the magnesium is bound to DNA, probably to its phosphate groups. Evidence is presented that the magnesium atoms combined with the phosphate groups of DNA are also attached to mononucleotides. There is reason to believe that those DNA-phosphate groups to which magnesium is bound, less than 1/10th of the total, are metabolically active, while those to which histones are attached seem to be inactive. PMID:13727745

Unraveling Metal-insulator Transition Mechanism of VO2 Triggered by Tungsten Doping

PubMed Central

Tan, Xiaogang; Yao, Tao; Long, Ran; Sun, Zhihu; Feng, Yajuan; Cheng, Hao; Yuan, Xun; Zhang, Wenqing; Liu, Qinghua; Wu, Changzheng; Xie, Yi; Wei, Shiqiang

2012-01-01

Understanding the mechanism of W-doping induced reduction of critical temperature (TC) for VO2 metal-insulator transition (MIT) is crucial for both fundamental study and technological application. Here, using synchrotron radiation X-ray absorption spectroscopy combined with first-principles calculations, we unveil the atomic structure evolutions of W dopant and its role in tailoring the TC of VO2 MIT. We find that the local structure around W atom is intrinsically symmetric with a tetragonal-like structure, exhibiting a concentration-dependent evolution involving the initial distortion, further repulsion, and final stabilization due to the strong interaction between doped W atoms and VO2 lattices across the MIT. These results directly give the experimental evidence that the symmetric W core drives the detwisting of the nearby asymmetric monoclinic VO2 lattice to form rutile-like VO2 nuclei, and the propagations of these W-encampassed nuclei through the matrix lower the thermal energy barrier for phase transition. PMID:22737402

The human sex odds at birth after the atmospheric atomic bomb tests, after Chernobyl, and in the vicinity of nuclear facilities.

PubMed

Scherb, Hagen; Voigt, Kristina

2011-06-01

Ever since the discovery of the mutagenic properties of ionizing radiation, the possibility of birth sex odds shifts in exposed human populations was considered in the scientific community. Positive evidence, however weak, was obtained after the atomic bombing of Japan. We previously investigated trends in the sex odds before and after the Chernobyl Nuclear Power Plant accident. In a pilot study, combined data from the Czech Republic, Denmark, Finland, Germany, Hungary, Norway, Poland, and Sweden between 1982 and 1992 showed a downward trend in the sex odds and a significant jump in 1987, the year immediately after Chernobyl. Moreover, a significant positive association of the sex odds between 1986 and 1991 with Chernobyl fallout at the district level in Germany was observed. Both of these findings, temporality (effect after exposure) and dose response association, yield evidence of causality. The primary aim of this study was to investigate longer time periods (1950-2007) in all of Europe and in the USA with emphasis on the global atmospheric atomic bomb test fallout and on the Chernobyl accident. To obtain further evidence, we also analyze sex odds data near nuclear facilities in Germany and Switzerland. DATA AND STATISTICAL METHODS: National gender-specific annual live births data for 39 European countries from 1975 to 2007 were compiled using the pertinent internet data bases provided by the World Health Organization, United Nations, Council of Europe, and EUROSTAT. For a synoptic re-analysis of the period 1950 to 1990, published data from the USA and from a predominantly western and less Chernobyl-exposed part of Europe were studied additionally. To assess spatial, temporal, as well as spatial-temporal trends in the sex odds and to investigate possible changes in those trends after the atomic bomb tests, after Chernobyl, and in the vicinity of nuclear facilities, we applied ordinary linear logistic regression. Region-specific and eventually changing spatial-temporal trends were analyzed using dummy variables coding for continents, countries, districts, municipalities, time periods, and appropriate spatial-temporal interactions. The predominantly western European sex odds trend together with the US sex odds trend (1950-1990 each) show a similar behavior. Both trends are consistent with a uniform reduction from 1950 to 1964, an increase from 1964 to 1975 that may be associated with delayed global atomic bomb test fallout released prior to the Partial Test Ban Treaty in 1963 and again a more or less constant decrease from 1975 to 1990. In practically all of Europe, including eastern European countries, from 1975 to 1986, and in the USA from 1975 to 2002, there were highly significant uniform downward trends in the sex odds with a reduction of 0.22% to 0.25% per 10 years. In contrast to the USA, in Europe there was a highly significant jump of the sex odds of 0.20% in the year 1987 following Chernobyl. From 1987 to 2000, the European sex odds trend reversed its sign and went upward, highly significantly so, with 0.42% per 10 years relative to the downward trend before Chernobyl. The global secular trend analyses are corroborated by the analysis of spatial-temporal sex odds trends near nuclear facilities (NF) in Germany and Switzerland. Within 35 km distance from those NF, the sex odds increase significantly in the range of 0.30% to 0.40% during NF operating time. The atmospheric atomic bomb test fallout affected the human sex odds at birth overall, and the Chernobyl fallout had a similar impact in Europe and parts of Asia. The birth sex odds near nuclear facilities are also distorted. The persistently disturbed secular human sex odds trends allow the estimation of the global deficit of births in the range of several millions.

Helium vs. Proton Induced Displacement Damage in Electronic Materials

NASA Technical Reports Server (NTRS)

Ringo, Sawnese; Barghouty, A. F.

2010-01-01

In this project, the specific effects of displacement damage due to the passage of protons and helium nuclei on some typical electronic materials will be evaluated and contrasted. As the electronic material absorbs the energetic proton and helium momentum, degradation of performance occurs, eventually leading to overall failure. Helium nuclei traveling at the same speed as protons are expected to impart more to the material displacement damage; due to the larger mass, and thus momentum, of helium nuclei compared to protons. Damage due to displacement of atoms in their crystalline structure can change the physical properties and hence performance of the electronic materials.

High resolution gamma-ray spectroscopy and the fascinating angular momentum realm of the atomic nucleus

NASA Astrophysics Data System (ADS)

Riley, M. A.; Simpson, J.; Paul, E. S.

2016-12-01

In 1974 Aage Bohr and Ben Mottelson predicted the different ‘phases’ that may be expected in deformed nuclei as a function of increasing angular momentum and excitation energy all the way up to the fission limit. While admitting their picture was highly conjectural they confidently stated ‘...with the ingenious experimental approaches that are being developed, we may look forward with excitement to the detailed spectroscopic studies that will illuminate the behaviour of the spinning quantised nucleus’. High resolution gamma-ray spectroscopy has indeed been a major tool in studying the structure of atomic nuclei and has witnessed numerous significant advances over the last four decades. This article will select highlights from investigations at the Niels Bohr Institute, Denmark, and Daresbury Laboratory, UK, in the late 1970s and early 1980s, some of which have continued at other national laboratories in Europe and the USA to the present day. These studies illustrate the remarkable diversity of phenomena and symmetries exhibited by nuclei in the angular momentum-excitation energy plane that continue to surprise and fascinate scientists.

Nuclear Spin Dependent Parity Violation in Diatomic Molecules

NASA Astrophysics Data System (ADS)

Cahn, Sidney; Altuntas, Emine; Ammon, Jeffrey; Demille, David

2015-10-01

Nuclear spin-dependent parity violation (NSD-PV) effects arise from the exchange of the Z0 boson between electrons and the nucleus and from the interaction of electrons with the nuclear anapole moment, a parity-odd magnetic moment. The anapole moment grows as A2/3 of the nucleus,while the Z0 coupling is independent of A. We study NSD-PV effects using diatomic molecules, where signals are dramatically amplified by bringing rotational levels of opposite parity close to degeneracy in a strong magnetic field. Using a Stark-interference technique, we measure the NSD-PV interaction matrix element. We present results that demonstrate statistical sensitivity to NSD-PV effects surpassing that of any previous atomic parity violation measurement, using the test system 138Ba19F. We also discuss improvements on investigations of systematics due to non-reversing stray E-fields, Enr together with B-field inhomogeneities, and short-term prospects for measuring the nuclear anapole moment of 137Ba. In the long term, our technique is sufficiently general and sensitive to enable measurements across a broad range of nuclei.

Theoretical and experimental {alpha} decay half-lives of the heaviest odd-Z elements and general predictions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, H. F.; Royer, G.

Theoretical {alpha} decay half-lives of the heaviest odd-Z nuclei are calculated using the experimental Q{sub {alpha}} value. The barriers in the quasimolecular shape path are determined within a Generalized Liquid Drop Model (GLDM) and the WKB approximation is used. The results are compared with calculations using the Density-Dependent M3Y (DDM3Y) effective interaction and the Viola-Seaborg-Sobiczewski (VSS) formulas. The calculations provide consistent estimates for the half-lives of the {alpha} decay chains of these superheavy elements. The experimental data stand between the GLDM calculations and VSS ones in the most time. Predictions are provided for the {alpha} decay half-lives of other superheavymore » nuclei within the GLDM and VSS approaches using the recent extrapolated Q{sub {alpha}} of Audi, Wapstra, and Thibault [Nucl. Phys. A729, 337 (2003)], which may be used for future experimental assignment and identification.« less

Hybrid configuration mixing model for odd nuclei

NASA Astrophysics Data System (ADS)

Colò, G.; Bortignon, P. F.; Bocchi, G.

2017-03-01

In this work, we introduce a new approach which is meant to be a first step towards complete self-consistent low-lying spectroscopy of odd nuclei. So far, we essentially limit ourselves to the description of a double-magic core plus an extra nucleon. The model does not contain any free adjustable parameter and is instead based on a Hartree-Fock (HF) description of the particle states in the core, together with self-consistent random-phase approximation (RPA) calculations for the core excitations. We include both collective and noncollective excitations, with proper care of the corrections due to the overlap between them (i.e., due to the nonorthonormality of the basis). As a consequence, with respect to traditional particle-vibration coupling calculations in which one can only address single-nucleon states and particle-vibration multiplets, we can also describe states of shell-model types like 2 particle-1 hole. We will report results for 49Ca and 133Sb and discuss future perspectives.

Momentum sharing in imbalanced Fermi systems

DOE PAGES

Hen, O.; Sargsian, M.; Weinstein, L. B.; ...

2014-10-16

The atomic nucleus is composed of two different kinds of fermions, protons and neutrons. If the protons and neutrons did not interact, the Pauli exclusion principle would force the majority fermions (usually neutrons) to have a higher average momentum. Our high-energy electron scattering measurements using 12C, 27Al, 56Fe and 208Pb targets show that, even in heavy neutron-rich nuclei, short-range interactions between the fermions form correlated high-momentum neutron-proton pairs. Thus, in neutron-rich nuclei, protons have a greater probability than neutrons to have momentum greater than the Fermi momentum. This finding has implications ranging from nuclear few body systems to neutron starsmore » and may also be observable experimentally in two-spin state, ultra-cold atomic gas systems.« less

Nuclear physics. Momentum sharing in imbalanced Fermi systems.

PubMed

Hen, O; Sargsian, M; Weinstein, L B; Piasetzky, E; Hakobyan, H; Higinbotham, D W; Braverman, M; Brooks, W K; Gilad, S; Adhikari, K P; Arrington, J; Asryan, G; Avakian, H; Ball, J; Baltzell, N A; Battaglieri, M; Beck, A; May-Tal Beck, S; Bedlinskiy, I; Bertozzi, W; Biselli, A; Burkert, V D; Cao, T; Carman, D S; Celentano, A; Chandavar, S; Colaneri, L; Cole, P L; Crede, V; D'Angelo, A; De Vita, R; Deur, A; Djalali, C; Doughty, D; Dugger, M; Dupre, R; Egiyan, H; El Alaoui, A; El Fassi, L; Elouadrhiri, L; Fedotov, G; Fegan, S; Forest, T; Garillon, B; Garcon, M; Gevorgyan, N; Ghandilyan, Y; Gilfoyle, G P; Girod, F X; Goetz, J T; Gothe, R W; Griffioen, K A; Guidal, M; Guo, L; Hafidi, K; Hanretty, C; Hattawy, M; Hicks, K; Holtrop, M; Hyde, C E; Ilieva, Y; Ireland, D G; Ishkanov, B I; Isupov, E L; Jiang, H; Jo, H S; Joo, K; Keller, D; Khandaker, M; Kim, A; Kim, W; Klein, F J; Koirala, S; Korover, I; Kuhn, S E; Kubarovsky, V; Lenisa, P; Levine, W I; Livingston, K; Lowry, M; Lu, H Y; MacGregor, I J D; Markov, N; Mayer, M; McKinnon, B; Mineeva, T; Mokeev, V; Movsisyan, A; Munoz Camacho, C; Mustapha, B; Nadel-Turonski, P; Niccolai, S; Niculescu, G; Niculescu, I; Osipenko, M; Pappalardo, L L; Paremuzyan, R; Park, K; Pasyuk, E; Phelps, W; Pisano, S; Pogorelko, O; Price, J W; Procureur, S; Prok, Y; Protopopescu, D; Puckett, A J R; Rimal, D; Ripani, M; Ritchie, B G; Rizzo, A; Rosner, G; Roy, P; Rossi, P; Sabatié, F; Schott, D; Schumacher, R A; Sharabian, Y G; Smith, G D; Shneor, R; Sokhan, D; Stepanyan, S S; Stepanyan, S; Stoler, P; Strauch, S; Sytnik, V; Taiuti, M; Tkachenko, S; Ungaro, M; Vlassov, A V; Voutier, E; Walford, N K; Wei, X; Wood, M H; Wood, S A; Zachariou, N; Zana, L; Zhao, Z W; Zheng, X; Zonta, I

2014-10-31

The atomic nucleus is composed of two different kinds of fermions: protons and neutrons. If the protons and neutrons did not interact, the Pauli exclusion principle would force the majority of fermions (usually neutrons) to have a higher average momentum. Our high-energy electron-scattering measurements using (12)C, (27)Al, (56)Fe, and (208)Pb targets show that even in heavy, neutron-rich nuclei, short-range interactions between the fermions form correlated high-momentum neutron-proton pairs. Thus, in neutron-rich nuclei, protons have a greater probability than neutrons to have momentum greater than the Fermi momentum. This finding has implications ranging from nuclear few-body systems to neutron stars and may also be observable experimentally in two-spin-state, ultracold atomic gas systems. Copyright © 2014, American Association for the Advancement of Science.

Method of controlling fusion reaction rates

DOEpatents

Kulsrud, Russell M.; Furth, Harold P.; Valeo, Ernest J.; Goldhaber, Maurice

1988-01-01

A method of controlling the reaction rates of the fuel atoms in a fusion reactor comprises the step of polarizing the nuclei of the fuel atoms in a particular direction relative to the plasma confining magnetic field. Fusion reaction rates can be increased or decreased, and the direction of emission of the reaction products can be controlled, depending on the choice of polarization direction.

Nuclear Stability and Nucleon-Nucleon Interactions in Introductory and General Chemistry Textbooks

ERIC Educational Resources Information Center

Millevolte, Anthony

2010-01-01

The nucleus is a highly dense and highly charged substructure of atoms. In the nuclei of all atoms beyond hydrogen, multiple protons are in close proximity to each other in spite of strong electrostatic repulsions between them. The attractive internucleon strong force is described and its origin explained by using a simple quark model for the…

Method of controlling fusion reaction rates

DOEpatents

Kulsrud, Russell M.; Furth, Harold P.; Valeo, Ernest J.; Goldhaber, Maurice

1988-03-01

A method of controlling the reaction rates of the fuel atoms in a fusion reactor comprises the step of polarizing the nuclei of the fuel atoms in a particular direction relative to the plasma confining magnetic field. Fusion reaction rates can be increased or decreased, and the direction of emission of the reaction products can be controlled, depending on the choice of polarization direction.

And so Ad Infinitum: The Search for Quark and Lepton Substructure

ERIC Educational Resources Information Center

Lincoln, Don

2018-01-01

The saga of the search for the ultimate constituents of matter has long been one of finding a seemingly fundamental structure that, in turn, was found to be made of even smaller building blocks. Matter is made of molecules. Molecules are in turn made of atoms, which are themselves made of electrons and atomic nuclei. The nucleus consists of…

Magnitude of finite-nucleus-size effects in relativistic density functional computations of indirect NMR nuclear spin-spin coupling constants.

PubMed

Autschbach, Jochen

2009-09-14

A spherical Gaussian nuclear charge distribution model has been implemented for spin-free (scalar) and two-component (spin-orbit) relativistic density functional calculations of indirect NMR nuclear spin-spin coupling (J-coupling) constants. The finite nuclear volume effects on the hyperfine integrals are quite pronounced and as a consequence they noticeably alter coupling constants involving heavy NMR nuclei such as W, Pt, Hg, Tl, and Pb. Typically, the isotropic J-couplings are reduced in magnitude by about 10 to 15 % for couplings between one of the heaviest NMR nuclei and a light atomic ligand, and even more so for couplings between two heavy atoms. For a subset of the systems studied, viz. the Hg atom, Hg(2) (2+), and Tl--X where X=Br, I, the basis set convergence of the hyperfine integrals and the coupling constants was monitored. For the Hg atom, numerical and basis set calculations of the electron density and the 1s and 6s orbital hyperfine integrals are directly compared. The coupling anisotropies of TlBr and TlI increase by about 2 % due to finite-nucleus effects.

Study to perform preliminary experiments to evaluate particle generation and characterization techniques for zero-gravity cloud physics experiments

NASA Technical Reports Server (NTRS)

Katz, U.

1982-01-01

Methods of particle generation and characterization with regard to their applicability for experiments requiring cloud condensation nuclei (CCN) of specified properties were investigated. Since aerosol characterization is a prerequisite to assessing performance of particle generation equipment, techniques for characterizing aerosol were evaluated. Aerosol generation is discussed, and atomizer and photolytic generators including preparation of hydrosols (used with atomizers) and the evaluation of a flight version of an atomizer are studied.

alpha-decay half-lives and Q{sub a}lpha values of superheavy nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong Jianmin; Graduate University of Chinese Academy of Sciences, Beijing 100049; School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000

2010-06-15

The alpha-decay half-lives of recently synthesized superheavy nuclei (SHN) are investigated by employing a unified fission model (UFM) where a new method to calculate the assault frequency of alpha emission is used. The excellent agreement with the experimental data indicates the UFM is a useful tool to investigate these alpha decays. It is found that the alpha-decay half-lives become more and more insensitive to the Q{sub a}lpha values as the atomic number increases on the whole, which is favorable for us to predict the half-lives of SHN. In addition, a formula is proposed to compute the Q{sub a}lpha values formore » the nuclei with Z>=92 and N>=140 with a good accuracy, according to which the long-lived SHN should be neutron rich. Several weeks ago, two isotopes of a new element with atomic number Z=117 were synthesized and their alpha-decay chains have been observed. The Q{sub a}lpha formula is found to work well for these nuclei, confirming its predictive power. The experimental half-lives are well reproduced by employing the UFM with the experimental Q{sub a}lpha values. This fact that the experimental half-lives are compatible with experimental Q{sub a}lpha values supports the synthesis of a new element 117 and the experimental measurements to a certain extent.« less

New dimensions of the periodic system: superheavy, superneutronic, superstrange, antimatter nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greiner, Walter

2010-12-23

The possibilities for the extension of the periodic system into the islands of superheavy (SH) elements, to and beyond the neutron drip line and to the sectors of strangeness and antimatter are discussed. The multi-nucleon transfer processes in low-energy damped collisions of heavy actinide nuclei may help us to fill the gap between the nuclei produced in the ''hot'' fusion reactions and the continent of known nuclei. In these reactions we may also investigate the ''island of stability''. In many such collisions the lifetime of the composite giant system consisting of two touching nuclei turns out to be rather longmore » ({>=}10{sup -20} s); sufficient for observing line structure in spontaneous positron emission from super-strong electric fields (vacuum decay), a fundamental QED process not observed yet experimentally. At the neutron-rich sector near the drip line islands and extended ridges of quasistable nuclei are predicted by HF calculations. Such nuclei, as well as very long living superheavy nuclei may be provided in double atomic bomb explosions. A tremendously rich scenario of new nuclear structure emerges with new magic numbers in the strangeness domain. Various production mechanisms are discussed for these objects and for antinuclei in high energy heavy-ion collisions.« less

Non-classical nuclei and growth kinetics of Cr precipitates in FeCr alloys during ageing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yulan; Hu, Shenyang Y.; Zhang, Lei

2014-01-10

In this manuscript, we quantitatively calculated the thermodynamic properties of critical nuclei of Cr precipitates in FeCr alloys. The concentration profiles of the critical nuclei and nucleation energy barriers were predicted by the constrained shrinking dimer dynamics (CSDD) method. It is found that Cr concentration distribution in the critical nuclei strongly depend on the overall Cr concentration as well as temperature. The critical nuclei are non-classical because the concentration in the nuclei is smaller than the thermodynamic equilibrium value. These results are in agreement with atomic probe observation. The growth kinetics of both classical and non-classical nuclei was investigated bymore » the phase field approach. The simulations of critical nucleus evolution showed a number of interesting phenomena: 1) a critical classical nucleus first shrinks toward its non-classical nucleus and then grows; 2) a non-classical nucleus has much slower growth kinetics at its earlier growth stage compared to the diffusion-controlled growth kinetics. 3) a critical classical nucleus grows faster at the earlier growth stage than the non-classical nucleus. All of these results demonstrate that it is critical to introduce the correct critical nuclei in order to correctly capture the kinetics of precipitation.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saperstein, E. E., E-mail: saper@mbslab.kiae.ru; Tolokonnikov, S. V.

Recent results obtained on the basis of the self-consistent theory of finite Fermi systems by employing the energy density functional proposed by Fayans and his coauthors are surveyed. These results are compared with the predictions of Skyrme–Hartree–Fock theory involving several popular versions of the Skyrme energy density functional. Spherical nuclei are predominantly considered. The charge radii of even and odd nuclei and features of low-lying 2{sup +} excitations in semimagic nuclei are discussed briefly. The single-particle energies ofmagic nuclei are examined inmore detail with allowance for corrections to mean-field theory that are induced by particle coupling to low-lying collective surfacemore » excitations (phonons). The importance of taking into account, in this problem, nonpole (tadpole) diagrams, which are usually disregarded, is emphasized. The spectroscopic factors of magic and semimagic nuclei are also considered. In this problem, only the surface term stemming from the energy dependence induced in the mass operator by the exchange of surface phonons is usually taken into account. The volume contribution associated with the energy dependence initially present in the mass operator within the self-consistent theory of finite Fermi systems because of the exchange of high-lying particle–hole excitations is also included in the spectroscopic factor. The results of the first studies that employed the Fayans energy density functional for deformed nuclei are also presented.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, J. B.; Hamilton, J. H.

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 ofmore » 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.« less

Gd(III) complexes as paramagnetic tags: Evaluation of the spin delocalization over the nuclei of the ligand

NASA Astrophysics Data System (ADS)

Collauto, A.; Feintuch, A.; Qi, M.; Godt, A.; Meade, T.; Goldfarb, D.

2016-02-01

Complexes of the Gd(III) ion are currently being established as spin labels for distance determination in biomolecules by pulse dipolar spectroscopy. Because Gd(III) is an f ion, one expects electron spin density to be localized on the Gd(III) ion - an important feature for the mentioned application. Most of the complex ligands have nitrogens as Gd(III) coordinating atoms. Therefore, measurement of the 14N hyperfine coupling gives access to information on the localization of the electron spin on the Gd(III) ion. We carried out W-band, 1D and 2D 14N and 1H ENDOR measurements on the Gd(III) complexes Gd-DOTA, Gd-538, Gd-595, and Gd-PyMTA that serve as spin labels for Gd-Gd distance measurements. The obtained 14N spectra are particularly well resolved, revealing both the hyperfine and nuclear quadrupole splittings, which were assigned using 2D Mims ENDOR experiments. Additionally, the spectral contributions of the two different types of nitrogen atoms of Gd-PyMTA, the aliphatic N atom and the pyridine N atom, were distinguishable. The 14N hyperfine interaction was found to have a very small isotropic hyperfine component of -0.25 to -0.37 MHz. Furthermore, the anisotropic hyperfine interactions with the 14N nuclei and with the non-exchangeable protons of the ligands are well described by the point-dipole approximation using distances derived from the crystal structures. We therefore conclude that the spin density is fully localized on the Gd(III) ion and that the spin density distribution over the nuclei of the ligands is rightfully ignored when analyzing distance measurements.

Electric field imaging of single atoms

PubMed Central

Shibata, Naoya; Seki, Takehito; Sánchez-Santolino, Gabriel; Findlay, Scott D.; Kohno, Yuji; Matsumoto, Takao; Ishikawa, Ryo; Ikuhara, Yuichi

2017-01-01

In scanning transmission electron microscopy (STEM), single atoms can be imaged by detecting electrons scattered through high angles using post-specimen, annular-type detectors. Recently, it has been shown that the atomic-scale electric field of both the positive atomic nuclei and the surrounding negative electrons within crystalline materials can be probed by atomic-resolution differential phase contrast STEM. Here we demonstrate the real-space imaging of the (projected) atomic electric field distribution inside single Au atoms, using sub-Å spatial resolution STEM combined with a high-speed segmented detector. We directly visualize that the electric field distribution (blurred by the sub-Å size electron probe) drastically changes within the single Au atom in a shape that relates to the spatial variation of total charge density within the atom. Atomic-resolution electric field mapping with single-atom sensitivity enables us to examine their detailed internal and boundary structures. PMID:28555629

Calculation of the atomic electric dipole moment of Pb2+ induced by nuclear Schiff moment

NASA Astrophysics Data System (ADS)

Ramachandran, S. M.; Latha, K. V. P.; Meenakshisundaram, N.

2017-07-01

We report the atomic electric dipole moment induced by the P, T violating interactions in the nuclear/sub-nuclear level, for 207Pb2+ and 207Pb, owing to the recent interest in the ferroelectric crystal PbTiO3 as one of the candidates for investigating macroscopic P, T-odd effects. In this paper, we calculate the atomic electric dipole moments of 207Pb and Pb2+, parametrized in terms of the P, T-odd coupling parameter, the nuclear Schiff moment (NSM), S, in the frame-work of the coupled-perturbed Hartree-Fock theory. We estimate the Schiff moment of Pb2+ using the experimental result of a system, which is electronically similar to the Pb2+ ion. We present the dominant contributions of the electric dipole moment (EDM) matrix elements and the important correlation effects contributing to the atomic EDM of Pb2+. Our results provide the first ever calculated EDM of the Pb2+ ion, and an estimate of its NSM from which the P, T-odd energy shift in a PbTiO3 crystal can be evaluated.

Relativistic Spin-Orbit Heavy Atom on the Light Atom NMR Chemical Shifts: General Trends Across the Periodic Table Explained.

PubMed

Vícha, Jan; Komorovsky, Stanislav; Repisky, Michal; Marek, Radek; Straka, Michal

2018-06-12

The importance of relativistic effects on the NMR parameters in heavy-atom (HA) compounds, particularly the SO-HALA (Spin-Orbit Heavy Atom on the Light Atom) effect on NMR chemical shifts, has been known for about 40 years. Yet, a general correlation between the electronic structure and SO-HALA effect has been missing. By analyzing 1 H NMR chemical shifts of the sixth-period hydrides (Cs-At), we discovered general electronic-structure principles and mechanisms that dictate the size and sign of the SO-HALA NMR chemical shifts. In brief, partially occupied HA valence shells induce relativistic shielding at the light atom (LA) nuclei, while empty HA valence shells induce relativistic deshielding. In particular, the LA nucleus is relativistically shielded in 5d 2 -5d 8 and 6p 4 HA hydrides and deshielded in 4f 0 , 5d 0 , 6s 0 , and 6p 0 HA hydrides. This general and intuitive concept explains periodic trends in the 1 H NMR chemical shifts along the sixth-period hydrides (Cs-At) studied in this work. We present substantial evidence that the introduced principles have a general validity across the periodic table and can be extended to nonhydride LAs. The decades-old question of why compounds with occupied frontier π molecular orbitals (MOs) cause SO-HALA shielding at the LA nuclei, while the frontier σ MOs cause deshielding is answered. We further derive connection between the SO-HALA NMR chemical shifts and Spin-Orbit-induced Electron Deformation Density (SO-EDD), a property that can be obtained easily from differential electron densities and can be represented graphically. SO-EDD provides an intuitive understanding of the SO-HALA effect in terms of the depletion/concentration of the electron density at LA nuclei caused by spin-orbit coupling due to HA in the presence of a magnetic field. Using an analogy between the SO-EDD concept and arguments from classic NMR theory, the complex question of the SO-HALA NMR chemical shifts becomes easily understandable for a wide chemical audience.

Papillary Microcarcinoma of the Thyroid among Atomic Bomb Survivors: Tumor Characteristics and Radiation Risk

PubMed Central

Hayashi, Yuzo; Lagarde, Frederic; Tsuda, Nobuo; Funamoto, Sachiyo; Preston, Dale L.; Koyama, Kojiro; Mabuchi, Kiyohiko; Ron, Elaine; Kodama, Kazunori; Tokuoka, Shoji

2009-01-01

Background Radiation exposure is an established cause of clinical thyroid cancer, but little is known about radiation effects on papillary microcarcinoma (PMC) of the thyroid, a relatively common subclinical thyroid malignancy. Because the incidence of these small thyroid cancers has been increasing, it is important to better understand them and their relationship to radiation. Methods PMCs were identified in a subset of 7659 members of the Life Span Study of atomic-bomb survivors who had archived autopsy or surgical materials. We conducted a pathology review of these specimens and evaluated the histological features of the tumors and the association between PMCs and thyroid radiation dose. Results From 1958 to1995, 458 PMCs were detected among 313 study subjects. The majority of cancers exhibited pathologic features of papillary thyroid cancers. Overall, 81% of the PMCs were of the sclerosing variant and 91% were nonencapsulated, psammoma bodies occurred in 13% and calcification was observed in 23%. Over 95% had papillary or papillary-follicular architecture and most displayed nuclear overlap, clear nuclei, and nuclear grooves. Several of these features increased with increasing tumor size, but no association was found with radiation dose. A significant radiation-dose response was found for the prevalence of PMCs (estimated excess odds ratio/Gy=0.57; 95% CI: 0.01-1.55), with the excess risk observed primarily among females. Conclusion Low-to-moderate doses of ionizing radiation appears to increase the risk of thyroid PMCs, even when exposure occurs during adulthood. PMID:20120034

A UHV compatible source for a highly polarized thermal atomic beam of radioactive 8Li

NASA Astrophysics Data System (ADS)

Jänsch, H. J.; Kirchner, G.; Kühlert, O.; Lisowski, M.; Paggel, J. J.; Platzer, R.; Schillinger, R.; Tilsner, H.; Weindel, C.; Winnefeld, H.; Fick, D.

2000-12-01

A beam of the radioactive isotope 8Li is prepared at thermal velocities. The nuclei are highly spin polarized by transverse optical pumping of the thermal beam. The installation is ultra-high vacuum (UHV) compatible in a non-UHV accelerator environment. Since the atomic beam is used in a surface science experiment, where contamination must be avoided, special emphasis is given to the vacuum coupling of the accelerator/ 8Li production/surface experimental areas. The atomic beam is produced by stopping the nuclear reaction products and evaporating them again from high-temperature graphite. To enhance the atomic beam, a novel tubular thermalizer is applied. The thermal polarized atomic beam intensity is approximately 5×10 8 atoms/s sr.

Is Einstein the Father of the Atomic Bomb

NASA Astrophysics Data System (ADS)

Lustig, Harry

2009-05-01

Soon after the American atomic bombs were dropped on Hiroshima and Nagasaki, the notion took hold in the popular mind that Albert Einstein was ``the father of the bomb.'' The claim of paternity rests on the belief that E=mc2 is what makes the release of enormous amounts of energy in the fission process possible and that the atomic bomb could not have been built without it. This is a misapprehension. Most physicists have known that all along. Nevertheless in his reaction to the opera Dr. Atomic, a prominent physicist claimed that Einstein's discovery that matter can be transformed into energy ``is precisely what made the bomb possible.'' In fact what makes the fission reaction and one of its applications,the atomic bomb, possible is the smaller binding energies of fission products compared to the binding energies of the nuclei that undergo fission.The binding energies of nuclei are a well understood consequence of the numbers and arrangements of protons and neutrons in the nucleus and of quantum-mechanical effects. The realization that composite systems have binding energies predates relativity. In the 19th century they were ascribed to potential and other forms of energy that reside in the system. With Einstein they became rest mass energy. While E=mc2 is not the cause of fission, measuring the masses of the participants in the reaction does permit an easy calculation of the kinetic energy that is released.

Feshbach Prize: New Phenomena and New Physics from Strongly-Correlated Quantum Matter

NASA Astrophysics Data System (ADS)

Carlson, Joseph A.

2017-01-01

Strongly correlated quantum matter is ubiquitous in physics from cold atoms to nuclei to the cold dense matter found in neutron stars. Experiments from table-top to the extremely large scale experiments including FRIB and LIGO will help determine the properties of matter across an incredible scale of distances and energies. Questions to be addressed include the existence of exotic states of matter in cold atoms and nuclei, the response of this correlated matter to external probes, and the behavior of matter in extreme astrophysical environments. A more complete understanding is required, both to understand these diverse phenomena and to employ this understanding to probe for new underlying physics in experiments including neutrinoless double beta decay and accelerator neutrino experiments. I will summarize some aspects of our present understanding and highlight several important prospects for the future.

Preface

NASA Astrophysics Data System (ADS)

Kowalska, Magdalena; Błaszczak, Zdzislaw

2017-11-01

It is with great pleasure that we are presenting the subsequent volume of the International Poznan Workshop proceedings. The conferences of this cycle have been since the beginning devoted to laser light interaction with atomic nuclei and since more recently also to the applications of ion-storage devices. The first edition entitled "Laser Spectroscopy of Atomic Nuclei" took place in Dubna in December 1990, and since then the subsequent conferences have been held every two to three years in Poznan, where they have been jointly organized by the Faculty of Physics at the Adam Mickiewicz University (Poznan) and the Flerov Laboratory of Nuclear Reactions at the Joint Institute of Nuclear Research (Dubna). The conferences have enjoyed increasing popularity and have attracted increasing numbers of specialists from a number of research institutions engaged in laser spectroscopy of radioactive and other exotic (e.g. anti-) atomic nuclei and related instruments. Over the years the workshops have gained a reputation of presenting research of a high scientific level and having impact on the directions of future studies. The 2016 workshop on the Application of Lasers and Storage Devices in Atomic Nuclei Research has been already the 10th edition and it was a pleasure to see that the event was thriving and the participants were enjoying it in all fronts. Around 100 scientists met on May 16 -19 in Poznan for the 4-day event. They were even more international than in the previous edition, representing institutes in Europe, North America, Japan, and even Australia. Many have returned to Poznan, but there were also new faces, especially among the younger participants. It was great to see the leaders in their topics discussing physics, but not only, with PhD students and starting post-docs. More than sixty talks were delivered, reflecting well the state-of-the art in the covered fields which were all related to the techniques, experimental results and theory connected to lasers and storage devices applied to exotic nuclei. The presentations were supplemented with many posters covering even more results. We hope that the participants also enjoyed the concert of renaissance music. In this warm atmosphere (much warmer than the temperatures outside the lecture hall), we are looking forward to the 11 th edition, which has been already announced to take place again in Poznan. In the next 3 years many new results will be certainly collected, so that without doubt we will participate in another interesting workshop.

All the observed universe has contributed to life.

PubMed

Davies, R E; Koch, R H

1991-12-30

This paper presents evidence that virtually all electrons and nuclei of the atoms that are or have been part of living matter on Earth came from almost all stars in our and nearby galaxies and even from all other galaxies in the Universe that have produced observed high-energy gamma rays. However, a standard 70 kg human is always making about 7 3He, 600 40Ca, and 3000 14N nuclei every second by radioactive decay of 3H, 40K, and 14C, respectively.

ORBITING CLUSTERS IN ATOMIC NUCLEI

PubMed Central

Pauling, Linus

1969-01-01

As an alternative to their description as vibrational levels, the low excited states of even-even nuclei can be described as rotational states of a helion, dineutron, diproton, or other cluster about the rest of the nucleus, leading to reasonable values of the average distance between centers of the clusters. Some states involve rotational excitation of two or more helions or other clusters. The nature of the rotating clusters is determined by the relation of the neutron and proton numbers to the magic numbers. PMID:16591799

Unusual chemical compositions of noctilucent-cloud particle nuclei

NASA Technical Reports Server (NTRS)

Hemenway, C. L.

1973-01-01

Two sounding rocket payloads were launched from the ESRO range in Sweden during a noctilucent cloud display. Large numbers of submicron particles were collected, most of which appear to be made up of a high density material coated with a low density material. Typical electron micrographs are shown. Particle chemical compositions have been measured by use of dispersive X-ray analysis equipment attached to an electron microscope and have revealed that most of the high density particle nuclei have atomic weights greater than iron.

Bimetallic Platinum-Rhodium Alloy Nanodendrites as Highly Active Electrocatalyst for the Ethanol Oxidation Reaction.

PubMed

Bai, Juan; Xiao, Xue; Xue, Yuan-Yuan; Jiang, Jia-Xing; Zeng, Jing-Hui; Li, Xi-Fei; Chen, Yu

2018-06-13

Rationally designing and manipulating composition and morphology of precious metal-based bimetallic nanostructures can markedly enhance their electrocatalytic performance, including selectivity, activity, and durability. We herein report the synthesis of bimetallic PtRh alloy nanodendrites (ANDs) with tunable composition by a facile complex-reduction synthetic method under hydrothermal conditions. The structural/morphologic features, formation mechanism, and electrocatalytic performance of PtRh ANDs are investigated thoroughly by various physical characterization and electrochemical methods. The preformed Rh crystal nuclei effectively catalyze the reduction of Pt 2+ precursor, resulting in PtRh alloy generation due to the catalytic growth and atoms interdiffusion process. The Pt atoms deposition distinctly interferes in Rh atoms deposition on Rh crystal nuclei, resulting in dendritic morphology of PtRh ANDs. For the ethanol oxidation reaction (EOR), PtRh ANDs display the chemical composition and solution pH co-dependent electrocatalytic activity. Because of the alloy effect and particular morphologic feature, Pt 1 Rh 1 ANDs with optimized composition exhibit better reactivity and stability for the EOR than commercial Pt nanocrystals electrocatalyst.

Isobar analog states (IAS), double isobar analog states (DIAS), configuration states (CS), and double configuration states (DCS) in halo nuclei. Halo isomers

NASA Astrophysics Data System (ADS)

Izosimov, I. N.

2015-10-01

It has been shown that IAS, DIAS, CS, and DCS can simultaneously have n-n, n-p, and p-p halo components in their wave functions. Differences in halo structure of the excited and ground states can result in the formation of isomers (halo-isomers). Both the Borromean and tango halo types can be observed for n-p configurations of atomic nuclei. The structure of the ground and excited states with different isospin quantum number in halo like nuclei is discussed. B(Mλ) and B(Eλ) for γ-transitions in 6,7,8Li, 8,9,10Be, 8,10,11B, 10,11,12,13,14C, 13,14,15,16,17N, 15,16,17,19O, and 17F are analyzed. Special attention is given to nuclei whose ground state does not exhibit halo structure but the excited state may have one.

The volatile composition of comets

NASA Technical Reports Server (NTRS)

Weaver, H. A.

1988-01-01

Comets may be our best probes of the physical and chemical conditions in the outer regions of the solar nebula during that crucial period when the planets formed. The volatile composition of cometary nuclei can be used to decide whether comets are the product of a condensation sequence similar to that invoked to explain the compositions of the planets and asteroids, or if comets are simply agglomerations of interstellar grains which have been insignificantly modified by the events that shaped the other bodies in the solar system. Although cometary nuclei are not generally accessible to observation, observations of cometary comae can illuminate at least some of the mysteries of the nuclei provided one has a detailed knowledge of the excitation conditions in the coma and also has access to basic atomic and molecular data on the many species present in comets. Examined here is the status of our knowledge of the volatile composition of cometary nuclei and how these data are obtained.

THE RADIATIVE NEUTRON CAPTURE ON 2H, 6Li, 7Li, 12C AND 13C AT ASTROPHYSICAL ENERGIES

NASA Astrophysics Data System (ADS)

Dubovichenko, Sergey; Dzhazairov-Kakhramanov, Albert; Burkova, Natalia

2013-05-01

The continued interest in the study of radiative neutron capture on atomic nuclei is due, on the one hand, to the important role played by this process in the analysis of many fundamental properties of nuclei and nuclear reactions, and, on the other hand, to the wide use of the capture cross-section data in the various applications of nuclear physics and nuclear astrophysics, and, also, to the importance of the analysis of primordial nucleosynthesis in the Universe. This paper is devoted to the description of results for the processes of the radiative neutron capture on certain light atomic nuclei at thermal and astrophysical energies. The consideration of these processes is done within the framework of the potential cluster model (PCM), general description of which was given earlier. The methods of usage of the results obtained, based on the phase shift analysis intercluster potentials, are demonstrated in calculations of the radiative capture characteristics. The considered capture reactions are not part of stellar thermonuclear cycles, but involve in the basic reaction chain of primordial nucleosynthesis in the course of the Universe formation.

Noise suppression for the differential detection in nuclear magnetic resonance gyroscope

NASA Astrophysics Data System (ADS)

Yang, Dan; Zhou, Binquan; Chen, LinLin; Jia, YuChen; Lu, QiLin

2017-10-01

The nuclear magnetic resonance gyroscope is based on spin-exchange optical pumping of noble gases to detect and measure the angular velocity of the carrier, but it would be challenging to measure the precession signal of noble gas nuclei directly. To solve the problem, the primary detection method utilizes alkali atoms, the precession of nuclear magnetization modulates the alkali atoms at the Larmor frequency of nuclei, relatively speaking, and it is easier to detect the precession signal of alkali atoms. The precession frequency of alkali atoms is detected by the rotation angle of linearly polarized probe light; and differential detection method is commonly used in NMRG in order to detect the linearly polarized light rotation angle. Thus, the detection accuracy of differential detection system will affect the sensitivity of the NMRG. For the purpose of further improvement of the sensitivity level of the NMRG, this paper focuses on the aspects of signal detection, and aims to do an error analysis as well as an experimental research of the linearly light rotation angle detection. Through the theoretical analysis and the experimental illustration, we found that the extinction ratio σ2 and DC bias are the factors that will produce detective noise in the differential detection method.

High spin states in 164Lu

NASA Astrophysics Data System (ADS)

Juneja, P.; Gupta, S. L.; Pancholi, S. C.; Kumar, Ashok; Mehta, D.; Chaturvedi, L.; Katoch, S. K.; Malik, S.; Shanker, G.; Bhowmik, R. K.; Muralithar, S.; Rodrigues, G.; Singh, R. P.

1996-03-01

High spin states in the odd-odd 164Lu nucleus have been investigated for the first time, through in-beam gamma-ray spectroscopy, following the 150Sm(19F,5n) reaction at beam energy Elab=105 MeV. Four bands, including two signature split bands are identified. The interpretation of the experimental results is discussed in comparison with the existing data in the neighboring nuclei and in the framework of the cranked shell model. The πh11/2⊗νi13/2 yrast band exhibits anomalous signature splitting and signature inversion is observed at a spin of 18ħ. This provides the missing datum for the systematics of staggering and signature inversion for the neighboring odd-odd N=93 isotones and supports the predictions of angular-momentum projection calculations by Hara and Sun. In the second signature split πh 11/2h9/2 band, the AB neutron crossing occurs at a rotational frequency of ~0.29 MeV. This is indicative of the disappearance of the blocking effect of the odd neutron.

Research with Radioactive Targets

NASA Astrophysics Data System (ADS)

Ahle, Larry

2004-10-01

Obtaining precise information about neutron capture cross-sections for s-process branch points is a key goal of nuclear astrophysics. Since these nuclei are unstable and neutron targets do not exist, performing these measurements require a facility that can produce the nuclei of interest at a sufficient rate to allow formation of a meaningful target (at least 1015 atoms). The Rare Isotope Accelerator (RIA) promises such rates, often enabling collection of greater than 1016 atoms after only of few days of production running. By properly designing both the ISOL and fragmentation lines, these collections will often be possible to obtained parasitically to other radioactive ion beam production. But given a target, performing the neutron capture cross-section measurement also presents its own challenges. In many cases, activation measurements are feasible, providing one obtains a target of sufficient purity. But for many branch point nuclei, the capture product is stable or long enough lived that no radiation signature is available for detection. Measurements for these nuclei will require a BaF2 array like DANCE at Los Alamos National Laboratory, which uses gamma calorimetry to detect neutron capture events. Plans and issues associated with isotope harvesting will be discussed, as well as challenges associated with performing theses measurements. Current plans for doing DANCE type measurements at RIA will also be discussed. This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

Shell Corrections Stabilizing Superheavy Nuclei and Semi-spheroidal Atomic Clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poenaru, Dorin N.

2008-01-24

The macroscopic-microscopic method is used to illustrate the shell effect stabilizing superheavy nuclei and to study the stability of semi-spheroidal clusters deposited on planar surfaces. The alpha decay of superheavy nuclei is calculated using three models: the analytical superasymmetric fission model; the universal curve, and the semiempirical formula taking into account the shell effects. Analytical relationships are obtained for the energy levels of the new semi-spheroidal harmonic oscillator (SSHO) single-particle model and for the surface and curvature energies of the semi-spheroidal clusters. The maximum degeneracy of the SSHO is reached at a super-deformed prolate shape for which the minimum ofmore » the liquid drop model energy is also attained.« less

The energy distribution of very heavy cosmic ray nuclei within the penumbra at Palestine, Texas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mathiesen, O.; Larsson, L.; Andersson, R.

1975-09-01

The low-energy end of the rigidity spectrum of cosmic ray nuclei with atomic numbers 7greater than or equal to18, recorded in a balloon flight conducted from Palestine, Texas, has been compared with a corresponding theoretical spectrum based on the computations by Shea and Smart. The two distributions are found to be in qualitative agreement with each other. The spread in apparent particle charge, caused by the theoretical distribution of particle velocity at Palestine, has been calculated for detectors with different response functions. The resulting structure of the predicted charge spectrum of iron group nuclei is found to be in goodmore » agreement with corresponding experimental data.« less

Microscopic description of fission in odd-mass uranium and plutonium nuclei with the Gogny energy density functional

NASA Astrophysics Data System (ADS)

Rodrıguez-Guzmán, R.; Robledo, L. M.

2017-12-01

The parametrization D1M of the Gogny energy density functional is used to study fission in the odd-mass Uranium and Plutonium isotopes with A=233, \\ldots , 249 within the framework of the Hartree-Fock-Bogoliubov (HFB) Equal Filling Approximation (EFA). Ground state quantum numbers and deformations, pairing energies, one-neutron separation energies, barrier heights and fission isomer excitation energies are given. Fission paths, collective masses and zero point rotational and vibrational quantum corrections are used to compute the systematic of the spontaneous fission half-lives t_{SF}, the masses and charges of the fission fragments as well as their intrinsic shapes. Although there exits a strong variance of the predicted fission rates with respect to the details involved in their computation, it is shown that both the specialization energy and the pairing quenching effects, taken into account fully variationally within the HFB-EFA blocking scheme, lead to larger spontaneous fission half-lives in odd-mass U and Pu nuclei as compared with the corresponding even-even neighbors. It is shown that modifications of a few percent in the strengths of the neutron and proton pairing fields can have a significant impact on the collective masses leading to uncertainties of several orders of magnitude in the predicted t_{SF} values. Alpha-decay lifetimes have also been computed using a parametrization of the Viola-Seaborg formula.

High spin states in 162Lu

NASA Astrophysics Data System (ADS)

Gupta, S. L.; Pancholi, S. C.; Juneja, P.; Mehta, D.; Kumar, Ashok; Bhowmik, R. K.; Muralithar, S.; Rodrigues, G.; Singh, R. P.

1997-09-01

An experimental investigation of the odd-odd 162Lu nucleus, following the 148Sm(19F,5n) reaction at beam energy Elab=112 MeV, has been performed through in-beam gamma-ray spectroscopy. It revealed three signature-split bands. The yrast band based on πh11/2⊗νi13/2 configuration exhibits anomalous signature splitting (the unfavored signature Routhian lying lower than the favored one) whose magnitude Δe'~25 keV, is considerably reduced in contrast to sizable normal signature splitting Δe'~125 and 60 keV observed in the yrast πh11/2 bands of the neighboring odd-A 161,163Lu nuclei, respectively. The signature inversion in this band occurs at spin ~20ħ (frequency=0.37 MeV). The second signature-split band, observed above the band crossing associated with the alignment of a pair of i13/2 quasineutrons, is a band based on the four-quasiparticle [πh11/2[523]7/2-⊗νh9/2[521]3/2-⊗(νi13/2)2], i.e., EABAp(Bp), configuration. The third signature-split band is also likely to be a four-quasiparticle band with configuration similar to the second band but involving F quasineutron, i.e., FABAp(Bp). The experimental results are discussed in comparison with the existing data in the neighboring nuclei and in the framework of the cranking shell model.

Facile synthesis of graphene on dielectric surfaces using a two-temperature reactor CVD system

NASA Astrophysics Data System (ADS)

Zhang, C.; Man, B. Y.; Yang, C.; Jiang, S. Z.; Liu, M.; Chen, C. S.; Xu, S. C.; Sun, Z. C.; Gao, X. G.; Chen, X. J.

2013-10-01

Direct deposition of graphene on a dielectric substrate is demonstrated using a chemical vapor deposition system with a two-temperature reactor. The two-temperature reactor is utilized to offer sufficient, well-proportioned floating Cu atoms and to provide a temperature gradient for facile synthesis of graphene on dielectric surfaces. The evaporated Cu atoms catalyze the reaction in the presented method. C atoms and Cu atoms respectively act as the nuclei for forming graphene film in the low-temperature zone and the zones close to the high-temperature zones. A uniform and high-quality graphene film is formed in an atmosphere of sufficient and well-proportioned floating Cu atoms. Raman spectroscopy, scanning electron microscopy and atomic force microscopy confirm the presence of uniform and high-quality graphene.

Electric Dipole Moment Measurements with Rare Isotopes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chupp, Timothy

The origin of matter is one of the deepest questions addressed by science and remains a mystery because our understanding of the Big Bang suggests that equal amounts of matter as antimatter would be created and annihilate leaving nothing from which stars, galaxies, planets and ultimately life as we know it was created. We know this is not the case in the universe, and so the explanation that the laws of physics can distinguish the difference of moving forward and backward in time and provide mechanisms that produce more matter that antimatter so that a little bit was left over.more » These same laws of physics affect our world today and would very slightly change the shape of an atom, stretching is along the direction of the spin of its nucleus. This subtle shape change has been searched in many systems - the neutron, atoms and molecules, but has not yet been detected, even as the motivation is strengthened by our understanding of their structure. We therefore look to new systems that have special features that make these effects stand out. Rare isotopes provide one possibility and specific radon atoms are our choice. We have developed techniques to make these measurements with short-lived radioactive atoms, studied the nuclei to provide deeper understanding of how these affect arise in such atoms (including radium) and developed new laser-based techniques to measure and control the magnetic fields necessary to perform these exquisitely sensitive measurements. In this work we have shown that radioactive radon atoms can be produced and transported to an apparatus that lines up the spins of the atoms. We have also shown that the nuclei of nearby radium are pear shaped and that the radon nuclei likely oscillate from one pear shape to its mirror reflection. We have also used the techniques which control nuclear spin to study the magnetic environment in a magnetically shielded room, which has the smallest magnetic field in a large volume in the universe. Measuring magnetic fields and detecting noble atoms' shapes using lasers will provide new techniques for these measurements and impact a broad range of applications including measurements of the neutron EDM. Harvesting rare isotopes at the future FRIB facility at Michigan State University will provide much stronger sources of the isotopes of radon and radium for future-generation experiments and also provide new isotopes for applications including medicine.« less

The Development of Materials for Structures and Radiation Shielding in Aerospace

NASA Technical Reports Server (NTRS)

Kiefer, Richard L.; Orwoll, Robert A.

2001-01-01

Polymeric materials on space vehicles and high-altitude aircraft win be exposed to highly penetrating radiations. These radiations come from solar flares and galactic cosmic rays (GCR). Radiation from solar flares consists primarily of protons with energies less than 1 GeV. On the other hand, GCR consist of nuclei with energies as high as 10(exp 10) GeV. Over 90% of the nuclei in GCR are protons and alpha particles, however there is a small but significant component of particles with atomic numbers greater than ten. Particles with high atomic number (Z) and high energy interact with very high specific ionization and thus represent a serious hazard for humans and electronic equipment on a spacecraft or on high-altitude commercial aircraft (most importantly for crew members who would have long exposures). Neutrons generated by reactions with the high energy particles also represent a hazard both for humans and electronic equipment.

Comparison of experimental and theoretical electron-impact-ionization triple-differential cross sections for ethane

NASA Astrophysics Data System (ADS)

Ali, Esam; Nixon, Kate; Murray, Andrew; Ning, Chuangang; Colgan, James; Madison, Don

2015-10-01

We have recently examined electron-impact ionization of molecules that have one large atom at the center, surrounded by H nuclei (H2O , N H3 , C H4 ). All of these molecules have ten electrons; however, they vary in their molecular symmetry. We found that the triple-differential cross sections (TDCSs) for the highest occupied molecular orbitals (HOMOs) were similar, as was the character of the HOMO orbitals which had a p -type "peanut" shape. In this work, we examine ethane (C2H6 ) which is a molecule that has two large atoms surrounded by H nuclei, so that its HOMO has a double-peanut shape. The experiment was performed using a coplanar symmetric geometry (equal final-state energies and angles). We find the TDCS for ethane is similar to the single-center molecules at higher energies, and is similar to a diatomic molecule at lower energies.

Isospin symmetry breaking and large-scale shell-model calculations with the Sakurai-Sugiura method

NASA Astrophysics Data System (ADS)

Mizusaki, Takahiro; Kaneko, Kazunari; Sun, Yang; Tazaki, Shigeru

2015-05-01

Recently isospin symmetry breaking for mass 60-70 region has been investigated based on large-scale shell-model calculations in terms of mirror energy differences (MED), Coulomb energy differences (CED) and triplet energy differences (TED). Behind these investigations, we have encountered a subtle problem in numerical calculations for odd-odd N = Z nuclei with large-scale shell-model calculations. Here we focus on how to solve this subtle problem by the Sakurai-Sugiura (SS) method, which has been recently proposed as a new diagonalization method and has been successfully applied to nuclear shell-model calculations.

Study of transitional doubly-odd /sup 186/Ir and /sup 184/Ir

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ben Braham, A.; Bourgeois, C.; Kilcher, P.

1987-12-10

The transitional doubly-odd iridium nuclei with A = 184 and 186 have been studied from the ..beta../sup +//EC decay of the corresponding platinum isotopes using the on-line mass separator ISOCELE. Configurations can be reasonably Attributed to the low-lying states of /sup 184/Ir in agreement with results already known. On the other hand an E3 transition observed in /sup 186/Ir suggests that the known long-lived 1.7h 2/sup -/ state is located at 137.5 keV above the 16h 5/sup +/ state, raising questions about structure of this latter state.

The Superheavy Elements and Anti-Gravity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anastasovski, Petar K.

2004-02-04

The essence of any propulsion concept is to overcome gravity. Anti-gravity is a natural means to achieve this. Thus, the technology to pursue anti-gravity, by using superheavy elements, may provide a new propulsion paradigm. The theory of superluminal relativity provides a hypothesis for existence of elements with atomic number up to Z = 145, some of which may possess anti-gravity properties. Analysis results show that curved space-time exists demonstrating both gravitic and anti-gravitic properties not only around nuclei but inside the nuclei as well. Two groups of elements (Z < 64 and 63 < Z <145) exist that demonstrate thesemore » capabilities. The nuclei of the first group of elements have the masses with only the property of gravity. The nuclei of the elements of the second group have the masses with both properties: gravity and anti-gravity in two different ranges of curved space-time around the nuclei.. The hypothetical element with Z = 145 is the unique among all elements whose nucleus has only anti-gravity property. It is proposed that this element be named Hawking, in honour of Stephen W. Hawking.« less

The Superheavy Elements and Anti-Gravity

NASA Astrophysics Data System (ADS)

Anastasovski, Petar K.

2004-02-01

The essence of any propulsion concept is to overcome gravity. Anti-gravity is a natural means to achieve this. Thus, the technology to pursue anti-gravity, by using superheavy elements, may provide a new propulsion paradigm. The theory of superluminal relativity provides a hypothesis for existence of elements with atomic number up to Z = 145, some of which may possess anti-gravity properties. Analysis results show that curved space-time exists demonstrating both gravitic and anti-gravitic properties not only around nuclei but inside the nuclei as well. Two groups of elements (Z < 64 and 63 < Z <145) exist that demonstrate these capabilities. The nuclei of the first group of elements have the masses with only the property of gravity. The nuclei of the elements of the second group have the masses with both properties: gravity and anti-gravity in two different ranges of curved space-time around the nuclei.. The hypothetical element with Z = 145 is the unique among all elements whose nucleus has only anti-gravity property. It is proposed that this element be named Hawking, in honour of Stephen W. Hawking.

Structural studies of chromatin and chromosomes. Progress report, March 15--September 15, 1997

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bradbury, E.M.

This study focused on the following: (1) the structure of chromatin and chromosomes by neutron and x-ray scatter and atomic force microscope; (2) the architecture of human sperm and the structure of sperm by atomic force microscopy (AFM); (3) genome-architecture and higher-order structures in human sperm nuclei; and (4) the effects of histone modifications on the structure of nucleosomes by protein DNA crosslinking method.

Incorporating nuclear vibrational energies into the "atom in molecules" analysis: An analytical study

NASA Astrophysics Data System (ADS)

Gharabaghi, Masumeh; Shahbazian, Shant

2017-04-01

The quantum theory of atoms in molecules (QTAIM) is based on the clamped nucleus paradigm and solely working with the electronic wavefunctions, so does not include nuclear vibrations in the AIM analysis. On the other hand, the recently extended version of the QTAIM, called the multi-component QTAIM (MC-QTAIM), incorporates both electrons and quantum nuclei, i.e., those nuclei treated as quantum waves instead of clamped point charges, into the AIM analysis using non-adiabatic wavefunctions. Thus, the MC-QTAIM is the natural framework to incorporate the role of nuclear vibrations into the AIM analysis. In this study, within the context of the MC-QTAIM, the formalism of including nuclear vibrational energy in the atomic basin energy is developed in detail and its contribution is derived analytically using the recently proposed non-adiabatic Hartree product nuclear wavefunction. It is demonstrated that within the context of this wavefunction, the quantum nuclei may be conceived pseudo-adiabatically as quantum oscillators and both isotropic harmonic and anisotropic anharmonic oscillator models are used to compute the zero-point nuclear vibrational energy contribution to the basin energies explicitly. Inspired by the results gained within the context of the MC-QTAIM analysis, a heuristic approach is proposed within the context of the QTAIM to include nuclear vibrational energy in the basin energy from the vibrational wavefunction derived adiabatically. The explicit calculation of the basin contribution of the zero-point vibrational energy using the uncoupled harmonic oscillator model leads to results consistent with those derived from the MC-QTAIM.

Incorporating nuclear vibrational energies into the "atom in molecules" analysis: An analytical study.

PubMed

Gharabaghi, Masumeh; Shahbazian, Shant

2017-04-21

The quantum theory of atoms in molecules (QTAIM) is based on the clamped nucleus paradigm and solely working with the electronic wavefunctions, so does not include nuclear vibrations in the AIM analysis. On the other hand, the recently extended version of the QTAIM, called the multi-component QTAIM (MC-QTAIM), incorporates both electrons and quantum nuclei, i.e., those nuclei treated as quantum waves instead of clamped point charges, into the AIM analysis using non-adiabatic wavefunctions. Thus, the MC-QTAIM is the natural framework to incorporate the role of nuclear vibrations into the AIM analysis. In this study, within the context of the MC-QTAIM, the formalism of including nuclear vibrational energy in the atomic basin energy is developed in detail and its contribution is derived analytically using the recently proposed non-adiabatic Hartree product nuclear wavefunction. It is demonstrated that within the context of this wavefunction, the quantum nuclei may be conceived pseudo-adiabatically as quantum oscillators and both isotropic harmonic and anisotropic anharmonic oscillator models are used to compute the zero-point nuclear vibrational energy contribution to the basin energies explicitly. Inspired by the results gained within the context of the MC-QTAIM analysis, a heuristic approach is proposed within the context of the QTAIM to include nuclear vibrational energy in the basin energy from the vibrational wavefunction derived adiabatically. The explicit calculation of the basin contribution of the zero-point vibrational energy using the uncoupled harmonic oscillator model leads to results consistent with those derived from the MC-QTAIM.

L. James Rainwater and the Atomic Nuclei

Science.gov Websites

described the experimental situation for nuclear quadrupole moments. It was a fortuitous situation made even given value after a lapse of time. Top Some links on this page may take you to non-federal websites

Relativistic well-tempered Gaussian basis sets for helium through mercury

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okada, S.; Matsuoka, O.

1989-10-01

Exponent parameters of the nonrelativistically optimized well-tempered Gaussian basis sets of Huzinaga and Klobukowski have been employed for Dirac--Fock--Roothaan calculations without their reoptimization. For light atoms He (atomic number {ital Z}=2)--Rh ({ital Z}=45), the number of exponent parameters used has been the same as the nonrelativistic basis sets and for heavier atoms Pd ({ital Z}=46)--Hg({ital Z}=80), two 2{ital p} (and three 3{ital d}) Gaussian basis functions have been augmented. The scheme of kinetic energy balance and the uniformly charged sphere model of atomic nuclei have been adopted. The qualities of the calculated basis sets are close to the Dirac--Fock limit.

Pair correlations in low-lying T =0 states of odd-odd nuclei with six nucleons

NASA Astrophysics Data System (ADS)

Fu, G. J.; Zhao, Y. M.; Arima, A.

2018-02-01

In this paper, we study pair correlations in low-lying T =0 states for two typical cases of odd-odd N =Z nuclei. The first case is six nucleons in a single j =9 /2 shell, for which we study the S -broken-pair approximation, the isoscalar spin-1 pair condensation, and the isoscalar spin-aligned pair condensation, with schematic interactions. In the second case, we study pair approximations and correlation energies for 22Na, 34Cl, 46V, 62Ga, and 94Ag in multi-j shells with effective interactions. A few T =0 states are found to be well represented by isoscalar nucleon pairs. The isoscalar spin-aligned pairs play an important role for the yrast T =0 states with I ˜2 j and I ˜Imax in 22Na, 46V, and 94Ag. The overlap between the isoscalar J =1 pair wave function and the shell-model wave function is around 0.5 for the I =1 ,3 states of 34Cl and the I =1 state of 94Ag. The I =9 state of 62Ga is very well described by the isoscalar J =3 pair condensation. The broken-pair approximation (which is similar to the 2-quasiparticle excitation of the isovector pair condensation) is appropriate for quite few states, such as the I =1 -3 states of 34Cl and the I =5 state of 62Ga. The correlation energies are presented in this paper. It is noted that the picture based on nucleon-pair wave functions is not always in agreement with the picture based on correlation energies.

Measurement of elliptic flow of light nuclei at √{sN N}=200 , 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV at the BNL Relativistic Heavy Ion Collider

NASA Astrophysics Data System (ADS)

Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Brandin, A. V.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chatterjee, A.; Chattopadhyay, S.; Chen, J. H.; Chen, X.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, S.; Gupta, A.; Guryn, W.; Hamad, A. I.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Horvat, S.; Huang, T.; Huang, X.; Huang, B.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Jentsch, A.; Jia, J.; Jiang, K.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikoła, D. P.; Kisel, I.; Kisiel, A.; Kochenda, L.; Koetke, D. D.; Kosarzewski, L. K.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kumar, L.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, X.; Li, C.; Li, X.; Li, Y.; Li, W.; Lin, T.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, R.; Ma, G. L.; Ma, Y. G.; Ma, L.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Matis, H. S.; McDonald, D.; McKinzie, S.; Meehan, K.; Mei, J. C.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V. A.; Olvitt, D.; Page, B. S.; Pak, R.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Pile, P.; Pluta, J.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Pruthi, N. K.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, M. K.; Sharma, B.; Shen, W. Q.; Shi, Z.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singha, S.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Solyst, W.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stepanov, M.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B.; Sun, X. M.; Sun, Z.; Sun, Y.; Surrow, B.; Svirida, D. N.; Tang, Z.; Tang, A. H.; Tarnowsky, T.; Tawfik, A.; Thäder, J.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Todoroki, T.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, Y.; Wang, G.; Wang, J. S.; Wang, H.; Wang, Y.; Wang, F.; Webb, G.; Webb, J. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xiao, Z. G.; Xie, W.; Xie, G.; Xin, K.; Xu, H.; Xu, Z.; Xu, J.; Xu, Y. F.; Xu, Q. H.; Xu, N.; Yang, Y.; Yang, S.; Yang, C.; Yang, Y.; Yang, Y.; Yang, Q.; Ye, Z.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, J.; Zhang, Y.; Zhang, X. P.; Zhang, Z.; Zhang, J. B.; Zhang, S.; Zhang, S.; Zhang, J.; Zhao, J.; Zhong, C.; Zhou, L.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

2016-09-01

We present measurements of second-order azimuthal anisotropy (v2) at midrapidity (|y |<1.0 ) for light nuclei d ,t ,3He (for √{sN N}=200 , 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV) and antinuclei d ¯ (√{sN N}=200 , 62.4, 39, 27, and 19.6 GeV) and ¯3He (√{sN N}=200 GeV) in the STAR (Solenoidal Tracker at RHIC) experiment. The v2 for these light nuclei produced in heavy-ion collisions is compared with those for p and p ¯. We observe mass ordering in nuclei v2(pT) at low transverse momenta (pT<2.0 GeV/c ). We also find a centrality dependence of v2 for d and d ¯. The magnitude of v2 for t and 3He agree within statistical errors. Light-nuclei v2 are compared with predictions from a blast-wave model. Atomic mass number (A ) scaling of light-nuclei v2(pT) seems to hold for pT/A <1.5 GeV /c . Results on light-nuclei v2 from a transport-plus-coalescence model are consistent with the experimental measurements.

Measurement of elliptic flow of light nuclei at s N N = 200 , 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV at the BNL Relativistic Heavy Ion Collider

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adamczyk, L.; Adkins, J. K.; Agakishiev, G.

Here we present measurements of second-order azimuthal anisotropy ( v 2 ) at midrapidity ( |y| < 1.0 ) for light nuclei d , t , 3He (formore » $$\\sqrt{s}$$$_{NN}$$ = 200 , 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV) and antinuclei$$\\bar{d}$$ ( $$\\sqrt{s}$$$_{NN}$$ = 200 , 62.4, 39, 27, and 19.6 GeV) and 3 ¯¯¯¯¯ He ( $$\\sqrt{s}$$$_{NN}$$ = 200 GeV) in the STAR (Solenoidal Tracker at RHIC) experiment. The v 2 for these light nuclei produced in heavy-ion collisions is compared with those for p and $$\\bar{p}$$. We observe mass ordering in nuclei v 2 ( p T) at low transverse momenta ( p T < 2.0 GeV/c). We also find a centrality dependence of v 2 for d and $$\\bar{d}$$ . The magnitude of v 2 for t and 3He agree within statistical errors. Light-nuclei v 2 are compared with predictions from a blast-wave model. Atomic mass number ( A ) scaling of light-nuclei v 2 (p T) seems to hold for p T / A < 1.5 GeV/c . Results on light-nuclei v 2 from a transport-plus-coalescence model are consistent with the experimental measurements.« less

Measurement of elliptic flow of light nuclei at s N N = 200 , 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV at the BNL Relativistic Heavy Ion Collider

DOE PAGES

Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; ...

2016-09-23

Here we present measurements of second-order azimuthal anisotropy ( v 2 ) at midrapidity ( |y| < 1.0 ) for light nuclei d , t , 3He (formore » $$\\sqrt{s}$$$_{NN}$$ = 200 , 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV) and antinuclei$$\\bar{d}$$ ( $$\\sqrt{s}$$$_{NN}$$ = 200 , 62.4, 39, 27, and 19.6 GeV) and 3 ¯¯¯¯¯ He ( $$\\sqrt{s}$$$_{NN}$$ = 200 GeV) in the STAR (Solenoidal Tracker at RHIC) experiment. The v 2 for these light nuclei produced in heavy-ion collisions is compared with those for p and $$\\bar{p}$$. We observe mass ordering in nuclei v 2 ( p T) at low transverse momenta ( p T < 2.0 GeV/c). We also find a centrality dependence of v 2 for d and $$\\bar{d}$$ . The magnitude of v 2 for t and 3He agree within statistical errors. Light-nuclei v 2 are compared with predictions from a blast-wave model. Atomic mass number ( A ) scaling of light-nuclei v 2 (p T) seems to hold for p T / A < 1.5 GeV/c . Results on light-nuclei v 2 from a transport-plus-coalescence model are consistent with the experimental measurements.« less

The Ehrenfest force field: Topology and consequences for the definition of an atom in a molecule.

PubMed

Martín Pendás, A; Hernández-Trujillo, J

2012-10-07

The Ehrenfest force is the force acting on the electrons in a molecule due to the presence of the other electrons and the nuclei. There is an associated force field in three-dimensional space that is obtained by the integration of the corresponding Hermitian quantum force operator over the spin coordinates of all of the electrons and the space coordinates of all of the electrons but one. This paper analyzes the topology induced by this vector field and its consequences for the definition of molecular structure and of an atom in a molecule. Its phase portrait reveals: that the nuclei are attractors of the Ehrenfest force, the existence of separatrices yielding a dense partitioning of three-dimensional space into disjoint regions, and field lines connecting the attractors through these separatrices. From the numerical point of view, when the Ehrenfest force field is obtained as minus the divergence of the kinetic stress tensor, the induced topology was found to be highly sensitive to choice of gaussian basis sets at long range. Even the use of large split valence and highly uncontracted basis sets can yield spurious critical points that may alter the number of attraction basins. Nevertheless, at short distances from the nuclei, in general, the partitioning of three-dimensional space with the Ehrenfest force field coincides with that induced by the gradient field of the electron density. However, exceptions are found in molecules where the electron density yields results in conflict with chemical intuition. In these cases, the molecular graphs of the Ehrenfest force field reveal the expected atomic connectivities. This discrepancy between the definition of an atom in a molecule between the two vector fields casts some doubts on the physical meaning of the integration of Ehrenfest forces over the basins of the electron density.

On the existence of Rydberg nuclear molecules

NASA Astrophysics Data System (ADS)

Bertulani, C. A.; Frederico, T.; Hussein, M. S.

2017-11-01

Present nuclear detection techniques prevents us from determining if the analogue of a Rydberg molecule exists for the nuclear case. But nothing in nature disallows their existence. As in the atomic case, Rydberg nuclear molecules would be a laboratory for new aspects and applications of nuclear physics. We propose that Rydberg nuclear molecules, which represent the exotic, halo nuclei version, such as 11Be +11Be, of the well known quasimolecules observed in stable nuclei such as 12C +12C, might be common structures that could manifest their existence along the dripline. A study of possible candidates and the expected structure of such exotic clustering of two halo nuclei: the Rydberg nuclear molecules, is made on the basis of three different methods. It is shown that such cluster structures might be stable and unexpectedly common.

Rules governing the composition of revolving clusters in quasiband and prolate-deformation states of atomic nuclei

PubMed Central

Pauling, Linus

1982-01-01

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 158Er 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

Thermodynamics of the clusterization process of cis isomers of unsaturated fatty acids at the air/water interface.

PubMed

Vysotsky, Yu B; Belyaeva, E A; Fainerman, V B; Vollhardt, D; Aksenenko, E V; Miller, R

2009-04-02

In the framework of the semiempirical PM3 method, the thermodynamic parameters of cis isomers of unsaturated carboxylic acids at the air/water interface are studied. The model systems used are unsaturated cis fatty acid of the composition Delta = 12-15 and omega = 6-11, where Delta and omega refer to the number of carbon atoms between the functional group and double bond, and that between the double bond and methyl group, respectively. For dimers, trimers, and tetramers of the four acid series, the thermodynamic parameters of clusterization are calculated. It is shown that the position of the double bond does not significantly affect the values of thermodynamic parameters of formation and clusterization of carboxylic acids for equal chain lengths (n = Delta + omega). The calculated results show that for cis unsaturated fatty acid with odd Delta values the spontaneous clusterization threshold corresponds to n = 17-18 carbon atoms in the alkyl chain, while for monounsaturated acids with even Delta values this threshold corresponds to n = 18-19 carbon atoms in the alkyl chain. These differences in the clusterization threshold between the acids with even and odd Delta values are attributed to the formation of additional intermolecular hydrogen bonds between the ketonic oxygen atom of one monomer and the hydrogen atom linked to the alpha-carbon atom of the second monomer for the acids with odd Delta values or between the hydroxyl oxygen atom of one monomer and hydrogen atom linked to the alpha-carbon atom of the second monomer for the acids with even Delta values. The results obtained in the study agree satisfactorily with our experimental data for cis unsaturated nervonic (Delta15, omega9) and erucic acids (Delta13, omega9), and published data for some fatty acids, namely cis-16-heptadecenoic (Delta16, omega1), cis-9-hexadecenoic (Delta7, omega9), cis-11-eicosenoic (Delta11, omega9) and cis-9-octadecenoic acid (Delta9, omega9).

Elementary Particles and Forces.

ERIC Educational Resources Information Center

Quigg, Chris

1985-01-01

Discusses subatomic particles (quarks, leptons, and others) revealed by higher accelerator energies. A connection between forces at this subatomic level has been established, and prospects are good for a description of forces that encompass binding atomic nuclei. Colors, fundamental interactions, screening, camouflage, electroweak symmetry, and…

Method and apparatus for transmutation of atomic nuclei

DOEpatents

Maenchen, John Eric; Ruiz, Carlos Leon

1998-01-01

Insuring a constant supply of radioisotopes is of great importance to medicine and industry. This invention addresses this problem, and helps to solve it by introducing a new apparatus for transmutation of isotopes which enables swift and flexible production on demand.

Nuclear equation of state from ground and collective excited state properties of nuclei

NASA Astrophysics Data System (ADS)

Roca-Maza, X.; Paar, N.

2018-07-01

This contribution reviews the present status on the available constraints to the nuclear equation of state (EoS) around saturation density from nuclear structure calculations on ground and collective excited state properties of atomic nuclei. It concentrates on predictions based on self-consistent mean-field calculations, which can be considered as an approximate realization of an exact energy density functional (EDF). EDFs are derived from effective interactions commonly fitted to nuclear masses, charge radii and, in many cases, also to pseudo-data such as nuclear matter properties. Although in a model dependent way, EDFs constitute nowadays a unique tool to reliably and consistently access bulk ground state and collective excited state properties of atomic nuclei along the nuclear chart as well as the EoS. For comparison, some emphasis is also given to the results obtained with the so called ab initio approaches that aim at describing the nuclear EoS based on interactions fitted to few-body data only. Bridging the existent gap between these two frameworks will be essential since it may allow to improve our understanding on the diverse phenomenology observed in nuclei. Examples on observations from astrophysical objects and processes sensitive to the nuclear EoS are also briefly discussed. As the main conclusion, the isospin dependence of the nuclear EoS around saturation density and, to a lesser extent, the nuclear matter incompressibility remain to be accurately determined. Experimental and theoretical efforts in finding and measuring observables specially sensitive to the EoS properties are of paramount importance, not only for low-energy nuclear physics but also for nuclear astrophysics applications.

Effective field theory description of halo nuclei

NASA Astrophysics Data System (ADS)

Hammer, H.-W.; Ji, C.; Phillips, D. R.

2017-10-01

Nuclear halos emerge as new degrees of freedom near the neutron and proton driplines. They consist of a core and one or a few nucleons which spend most of their time in the classically-forbidden region outside the range of the interaction. Individual nucleons inside the core are thus unresolved in the halo configuration, and the low-energy effective interactions are short-range forces between the core and the valence nucleons. Similar phenomena occur in clusters of 4He atoms, cold atomic gases near a Feshbach resonance, and some exotic hadrons. In these weakly-bound quantum systems universal scaling laws for s-wave binding emerge that are independent of the details of the interaction. Effective field theory (EFT) exposes these correlations and permits the calculation of non-universal corrections to them due to short-distance effects, as well as the extension of these ideas to systems involving the Coulomb interaction and/or binding in higher angular-momentum channels. Halo nuclei exhibit all these features. Halo EFT, the EFT for halo nuclei, has been used to compute the properties of single-neutron, two-neutron, and single-proton halos of s-wave and p-wave type. This review summarizes these results for halo binding energies, radii, Coulomb dissociation, and radiative capture, as well as the connection of these properties to scattering parameters, thereby elucidating the universal correlations between all these observables. We also discuss how Halo EFT's encoding of the long-distance physics of halo nuclei can be used to check and extend ab initio calculations that include detailed modeling of their short-distance dynamics.

Feasibility of Harvesting Radon from FRIB Beam Dump

DOE Office of Scientific and Technical Information (OSTI.GOV)

Visser, A.; Scielzo, N.

The observation of a permanent electric dipole moment (EDM) in an atom would signal a long-soughtafter presence of time-reversal violation and would have far reaching consequences for both particle physics and cosmology. Currently, the most stringent limitation on time-reversal violating effects in the nucleus comes from studies of stable 199Hg. However, for certain nuclei which have an octupole deformed shape, such as 223Rn, the time-reversal violating interactions are expected to be 100-1000 times greater than in 199Hg (Auerbach et al. 1996). As a result, there is great interest in searching for EDMs in octupole deformed nuclei and some of themore » initial studies of these nuclei have been featured on the cover of the journal Nature (Gaffney et al. 2013). All the octupole deformed nuclei of interest are radioactive and therefore available only in limited quantities. The primary challenge for an EDM experiment using radon is to collect large enough samples to perform sensitive searches.« less

Isobar analog states (IAS), double isobar analog states (DIAS), configuration states (CS), and double configuration states (DCS) in halo nuclei. Halo isomers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Izosimov, I. N., E-mail: izosimov@jinr.ru

2015-10-15

It has been shown that IAS, DIAS, CS, and DCS can simultaneously have n-n, n-p, and p-p halo components in their wave functions. Differences in halo structure of the excited and ground states can result in the formation of isomers (halo-isomers). Both the Borromean and tango halo types can be observed for n-p configurations of atomic nuclei. The structure of the ground and excited states with different isospin quantum number in halo like nuclei is discussed. B(Mλ) and B(Eλ) for γ-transitions in {sup 6,7,8}Li, {sup 8,9,10}Be, {sup 8,10,11}B, {sup 10,11,12,13,14}C, {sup 13,14,15,16,17}N, {sup 15,16,17,19}O, and {sup 17}F are analyzed. Specialmore » attention is given to nuclei whose ground state does not exhibit halo structure but the excited state may have one.« less

A Molecular–Structure Hypothesis

PubMed Central

Boeyens, Jan C. A.

2010-01-01

The self-similar symmetry that occurs between atomic nuclei, biological growth structures, the solar system, globular clusters and spiral galaxies suggests that a similar pattern should characterize atomic and molecular structures. This possibility is explored in terms of the current molecular structure-hypothesis and its extension into four-dimensional space-time. It is concluded that a quantum molecule only has structure in four dimensions and that classical (Newtonian) structure, which occurs in three dimensions, cannot be simulated by quantum-chemical computation. PMID:21151437

Quantum molecular dynamics simulations of dense matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Collins, L.; Kress, J.; Troullier, N.

1997-12-31

The authors have developed a quantum molecular dynamics (QMD) simulation method for investigating the properties of dense matter in a variety of environments. The technique treats a periodically-replicated reference cell containing N atoms in which the nuclei move according to the classical equations-of-motion. The interatomic forces are generated from the quantum mechanical interactions of the (between?) electrons and nuclei. To generate these forces, the authors employ several methods of varying sophistication from the tight-binding (TB) to elaborate density functional (DF) schemes. In the latter case, lengthy simulations on the order of 200 atoms are routinely performed, while for the TB,more » which requires no self-consistency, upwards to 1000 atoms are systematically treated. The QMD method has been applied to a variety cases: (1) fluid/plasma Hydrogen from liquid density to 20 times volume-compressed for temperatures of a thousand to a million degrees Kelvin; (2) isotopic hydrogenic mixtures, (3) liquid metals (Li, Na, K); (4) impurities such as Argon in dense hydrogen plasmas; and (5) metal/insulator transitions in rare gas systems (Ar,Kr) under high compressions. The advent of parallel versions of the methods, especially for fast eigensolvers, presage LDA simulations in the range of 500--1000 atoms and TB runs for tens of thousands of particles. This leap should allow treatment of shock chemistry as well as large-scale mixtures of species in highly transient environments.« less

Cold nuclear fusion

NASA Astrophysics Data System (ADS)

Tsyganov, E. N.; Bavizhev, M. D.; Buryakov, M. G.; Dabagov, S. B.; Golovatyuk, V. M.; Lobastov, S. P.

2015-07-01

If target deuterium atoms were implanted in a metal crystal in accelerator experiments, a sharp increase in the probability of DD-fusion reaction was clearly observed when compared with the reaction's theoretical value. The electronic screening potential, which for a collision of free deuterium atoms is about 27 eV, reached 300-700 eV in the case of the DD-fusion in metallic crystals. These data leads to the conclusion that a ban must exist for deuterium atoms to be in the ground state 1s in a niche filled with free conduction electrons. At the same time, the state 2p whose energy level is only 10 eV above that of state 1s is allowed in these conditions. With anisotropy of 2p, 3p or above orbitals, their spatial positions are strictly determined in the lattice coordinate system. When filling out the same potential niches with two deuterium atoms in the states 2p, 3p or higher, the nuclei of these atoms can be permanently positioned without creating much Coulomb repulsion at a very short distance from each other. In this case, the transparency of the potential barrier increases dramatically compared to the ground state 1s for these atoms. The probability of the deuterium nuclei penetrating the Coulomb barrier by zero quantum vibration of the DD-system also increases dramatically. The so-called cold nuclear DD-fusion for a number of years was registered in many experiments, however, was still rejected by mainstream science for allegedly having no consistent scientific explanation. Finally, it received the validation. Below, we outline the concept of this explanation and give the necessary calculations. This paper also considers the further destiny of the formed intermediate state of 4He∗.

Method and apparatus for transmutation of atomic nuclei

DOEpatents

Maenchen, J.E.; Ruiz, C.L.

1998-12-08

Insuring a constant supply of radioisotopes is of great importance to medicine and industry. This invention addresses this problem, and helps to solve it by introducing a new apparatus for transmutation of isotopes which enables swift and flexible production on demand. 9 figs.

Method and apparatus for transmutation of atomic nuclei

DOEpatents

Maenchen, J.E.; Ruiz, C.L.

1998-06-09

Insuring a constant supply of radioisotopes is of great importance to medicine and industry. This invention addresses this problem, and helps to solve it by introducing a new apparatus for transmutation of isotopes which enables swift and flexible production on demand. 9 figs.

Doubly magic nuclei from lattice QCD forces at MPS=469 MeV /c2

NASA Astrophysics Data System (ADS)

McIlroy, C.; Barbieri, C.; Inoue, T.; Doi, T.; Hatsuda, T.

2018-02-01

We perform ab initio self-consistent Green's function calculations of the closed shell nuclei 4He, 16O, and 40Ca, based on two-nucleon potentials derived from lattice QCD simulations, in the flavor SU(3) limit and at the pseudoscalar meson mass of 469 MeV/c2. The nucleon-nucleon interaction is obtained using the hadrons-to-atomic-nuclei-from-lattice (HAL) QCD method, and its short-distance repulsion is treated by means of ladder resummations outside the model space. Our results show that this approach diagonalizes ultraviolet degrees of freedom correctly. Therefore, ground-state energies can be obtained from infrared extrapolations even for the relatively hard potentials of HAL QCD. Comparing to previous Brueckner Hartree-Fock calculations, the total binding energies are sensibly improved by the full account of many-body correlations. The results suggest an interesting possible behavior in which nuclei are unbound at very large pion masses and islands of stability appear at first around the traditional doubly magic numbers when the pion mass is lowered toward its physical value. The calculated one-nucleon spectral distributions are qualitatively close to those of real nuclei even for the pseudoscalar meson mass considered here.

First observation of rotational structures in Re 168

DOE PAGES

Hartley, D. J.; Janssens, R. V. F.; Riedinger, L. L.; ...

2016-11-30

We assigned first rotational sequences to the odd-odd nucleus 168Re. Coincidence relationships of these structures with rhenium x rays confirm the isotopic assignment, while arguments based on the γ-ray multiplicity (K-fold) distributions observed with the new bands lead to the mass assignment. Configurations for the two bands were determined through analysis of the rotational alignments of the structures and a comparison of the experimental B(M1)/B(E2) ratios with theory. Tentative spin assignments are proposed for the πh 11/2νi 13/2 band, based on energy level systematics for other known sequences in neighboring odd-odd rhenium nuclei, as well as on systematics seen formore » the signature inversion feature that is well known in this region. Furthermore, the spin assignment for the πh 11/2ν(h 9/2/f 7/2) structure provides additional validation of the proposed spins and configurations for isomers in the 176Au → 172Ir → 168Re α-decay chain.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hartley, D. J.; Janssens, R. V. F.; Riedinger, L. L.

We assigned first rotational sequences to the odd-odd nucleus 168Re. Coincidence relationships of these structures with rhenium x rays confirm the isotopic assignment, while arguments based on the γ-ray multiplicity (K-fold) distributions observed with the new bands lead to the mass assignment. Configurations for the two bands were determined through analysis of the rotational alignments of the structures and a comparison of the experimental B(M1)/B(E2) ratios with theory. Tentative spin assignments are proposed for the πh 11/2νi 13/2 band, based on energy level systematics for other known sequences in neighboring odd-odd rhenium nuclei, as well as on systematics seen formore » the signature inversion feature that is well known in this region. Furthermore, the spin assignment for the πh 11/2ν(h 9/2/f 7/2) structure provides additional validation of the proposed spins and configurations for isomers in the 176Au → 172Ir → 168Re α-decay chain.« less

Nucleation in Sheared Granular Matter

NASA Astrophysics Data System (ADS)

Rietz, Frank; Radin, Charles; Swinney, Harry L.; Schröter, Matthias

2018-02-01

We present an experiment on crystallization of packings of macroscopic granular spheres. This system is often considered to be a model for thermally driven atomic or colloidal systems. Cyclically shearing a packing of frictional spheres, we observe a first order phase transition from a disordered to an ordered state. The ordered state consists of crystallites of mixed fcc and hcp symmetry that coexist with the amorphous bulk. The transition, initiated by homogeneous nucleation, overcomes a barrier at 64.5% volume fraction. Nucleation consists predominantly of the dissolving of small nuclei and the growth of nuclei that have reached a critical size of about ten spheres.

Parity and Time-Reversal Violation in Atomic Systems

NASA Astrophysics Data System (ADS)

Roberts, B. M.; Dzuba, V. A.; Flambaum, V. V.

2015-10-01

Studying the violation of parity and time-reversal invariance in atomic systems has proven to be a very effective means of testing the electroweak theory at low energy and searching for physics beyond it. Recent developments in both atomic theory and experimental methods have led to the ability to make extremely precise theoretical calculations and experimental measurements of these effects. Such studies are complementary to direct high-energy searches, and can be performed for only a fraction of the cost. We review the recent progress in the field of parity and time-reversal violation in atoms, molecules, and nuclei, and examine the implications for physics beyond the Standard Model, with an emphasis on possible areas for development in the near future.

Nucleation of the diamond phase in aluminium-solid solutions

NASA Technical Reports Server (NTRS)

Hornbogen, E.; Mukhopadhyay, A. K.; Starke, E. A., Jr.

1993-01-01

Precipitation was studied from fcc solid solutions with silicon, germanium, copper and magnesium. Of all these elements only silicon and germanium form diamond cubic (DC) precipitates in fcc Al. Nucleation of the DC structure is enhanced if both types of atom are dissolved in the fcc lattice. This is interpreted as due to atomic size effects in the prenucleation stage. There are two modes of interference of fourth elements with nucleation of the DC phase in Al + Si, Ge. The formation of the DC phase is hardly affected if the atoms (for example, copper) are rejected from the (Si, Ge)-rich clusters. If additional types of atom are attracted by silicon and/or germanium, DC nuclei are replaced by intermetallic compounds (for example Mg2Si).

How large are nonadiabatic effects in atomic and diatomic systems?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Yubo, E-mail: yyang173@illinois.edu, E-mail: normantubman2015@u.northwestern.edu; Tubman, Norm M., E-mail: yyang173@illinois.edu, E-mail: normantubman2015@u.northwestern.edu; Ceperley, David M.

2015-09-28

With recent developments in simulating nonadiabatic systems to high accuracy, it has become possible to determine how much energy is attributed to nuclear quantum effects beyond zero-point energy. In this work, we calculate the non-relativistic ground-state energies of atomic and molecular systems without the Born-Oppenheimer approximation. For this purpose, we utilize the fixed-node diffusion Monte Carlo method, in which the nodes depend on both the electronic and ionic positions. We report ground-state energies for all systems studied, ionization energies for the first-row atoms and atomization energies for the first-row hydrides. We find the ionization energies of the atoms to bemore » nearly independent of the Born-Oppenheimer approximation, within the accuracy of our results. The atomization energies of molecular systems, however, show small effects of the nonadiabatic coupling between electrons and nuclei.« less

How large are nonadiabatic effects in atomic and diatomic systems?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Yubo; Kylänpää, Ilkka; Tubman, Norm M.

2015-09-29

With recent developments in simulating nonadiabatic systems to high accuracy, it has become possible to determine how much energy is attributed to nuclear quantum effects beyond zero-point energy. Here, we calculate the non-relativistic ground-state energies of atomic and molecular systems without the Born-Oppenheimer approximation. For this purpose, we utilize the fixed-node diffusion Monte Carlo method, in which the nodes depend on both the electronic and ionic positions. Our report shows the ground-state energies for all systems studied, ionization energies for the first-row atoms and atomization energies for the first-row hydrides. We find the ionization energies of the atoms to bemore » nearly independent of the Born-Oppenheimer approximation, within the accuracy of our results. The atomization energies of molecular systems, however, show small effects of the nonadiabatic coupling between electrons and nuclei.« less

High-seniority states in spherical nuclei: Triple pair breaking in tin isotopes

NASA Astrophysics Data System (ADS)

Astier, Alain

2013-03-01

The 119-126Sn nuclei have been produced as fission fragments in two reactions induced by heavy ions: 12C+238U at 90 MeV bombarding energy, 18O+208Pb at 85 MeV. Their level schemes have been built from gamma rays detected using the Euroball array. High-spin states located above the long-lived isomeric states of the even- A and odd-A 120-126Sn nuclei have been identified. Moreover isomeric states lying around 4.5 MeV have been established in the even-A 120-126Sn from the delayed coincidences between the fission fragment detector SAPhIR and the Euroball array. All the states located above 3-MeV excitation energy are ascribed to several broken pairs of neutrons occupying the h11/2 orbit. The maximum value of angular momentum available in such a high-j shell, i.e. for mid-occupation and the breaking of the three neutron pairs (seniority v=6), has been identified.

Role of neutrons and protons in entropy, spin cut off parameters, and moments of inertia

NASA Astrophysics Data System (ADS)

Razavi, R.

2013-07-01

The nuclear level densities, spin cut off parameters, and entropies have been extracted in 116-119Sn and 162,163Dy nuclei using superconducting theory, which includes nuclear pairing interaction. The results agree well with the recent data obtained from experimental level densities by the Oslo group for these nuclei. Also, the entropy excess ratio proposed by Razavi [R. Razavi, A.N. Behkami, S. Mohammadi, and M. Gholami, Phys. Rev. CPRVCAN0556-281310.1103/PhysRevC.86.047303 86, 047303 (2012)] for a proton and neutron as a function of nuclear temperature have been evaluated and are compared with the spin cut off excess ratio. The role of the neutron (proton) system is well determined by the entropy excess ratio as well as the spin cut off excess ratio. The moment of inertia for even-odd and even-even nuclei are also compared. The moment of inertia carried by a single hole is smaller than the single particle moment of inertia.

NMR spectra of androstane analogs of brassinosteroids

NASA Astrophysics Data System (ADS)

Baranovskii, A. V.; Litvinovskaya, R. P.; Aver'kova, M. A.; Khripach, N. B.; Khripach, V. A.

2007-09-01

We have used two-dimensional NMR spectroscopy to make a complete assignment of signals from the nuclei of hydrogen and carbon atoms in the spectra of brassinosteroids in the androstane series. We have confirmed the stereochemistry of the chiral centers and the structure of the molecules. We have studied the effect of the configuration of the 2,3-diol groups in the A ring of the steroids on the chemical shift of adjacent atoms in the 13C and 1H NMR spectra.

Evolution of nuclear structure in neutron-rich odd-Zn isotopes and isomers

NASA Astrophysics Data System (ADS)

Wraith, C.; Yang, X. F.; Xie, L.; Babcock, C.; Bieroń, J.; Billowes, J.; Bissell, M. L.; Blaum, K.; Cheal, B.; Filippin, L.; Garcia Ruiz, R. F.; Gins, W.; Grob, L. K.; Gaigalas, G.; Godefroid, M.; Gorges, C.; Heylen, H.; Honma, M.; Jönsson, P.; Kaufmann, S.; Kowalska, M.; Krämer, J.; Malbrunot-Ettenauer, S.; Neugart, R.; Neyens, G.; Nörtershäuser, W.; Nowacki, F.; Otsuka, T.; Papuga, J.; Sánchez, R.; Tsunoda, Y.; Yordanov, D. T.

2017-08-01

Collinear laser spectroscopy was performed on Zn (Z = 30) isotopes at ISOLDE, CERN. The study of hyperfine spectra of nuclei across the Zn isotopic chain, N = 33- 49, allowed the measurement of nuclear spins for the ground and isomeric states in odd-A neutron-rich nuclei up to N = 50. Exactly one long-lived (>10 ms) isomeric state has been established in each 69-79Zn isotope. The nuclear magnetic dipole moments and spectroscopic quadrupole moments are well reproduced by large-scale shell-model calculations in the f5pg9 and fpg9d5 model spaces, thus establishing the dominant term in their wave function. The magnetic moment of the intruder Iπ = 1 /2+ isomer in 79Zn is reproduced only if the νs1/2 orbital is added to the valence space, as realized in the recently developed PFSDG-U interaction. The spin and moments of the low-lying isomeric state in 73Zn suggest a strong onset of deformation at N = 43, while the progression towards 79Zn points to the stability of the Z = 28 and N = 50 shell gaps, supporting the magicity of 78Ni.

A Metastability-Exchange Optical Pumping and Compression System using Polarized 3 He for a Proposed Laboratory Search for Neutron Monopole-Dipole Interactions

NASA Astrophysics Data System (ADS)

Smith, Erick; Ariadne Collaboration

2015-04-01

3 He nuclei polarized using the metastability-exchange optical pumping (MEOP) method have been used for scientific applications such as magnetometry in space, neutron polarization and analysis, and medical imaging. In this talk we explain how this technique is also well-suited for a proposed experiment to search for possible monopole-dipole interactions of polarized 3 He nuclei with matter. The P-odd and T-odd monopole-dipole potential proposed by Moody and Wilczek is proportional to s-> . r-> where s-> is the 3 He spin and r-> is the separation between the particles. It can be induced by axions, and ARIADNE proposes to perform NMR on a polarized 3 He ensemble at 4K with a radially-slotted tungsten disk spinning at a multiple of the 3 He Larmour frequency to induce a resonant monopole-dipole perturbation. The radial slot length variations are chosen to maximize sensitivity to a monopole-dipole interaction range corresponding to the axion window. We describe the advantages that MEOP presents for this experiment and describe the MEOP-based polarized 3 He gas compression system at Indiana University.

Magnetic moments and g-factors in odd-A Ho isotopes

NASA Astrophysics Data System (ADS)

Tabar, E.; Yakut, H.; Kuliev, A. A.; Quliyev, H.; Hocşgör, G.

2017-07-01

The ground-state magnetic moment, g K factor and quenching spin gyromagnetic ratio have been calculated using the microscopic method based on the Quasiparticle Phonon Nuclear Model (QPNM) for 155-169Ho nuclei for the first time. It is shown that the residual spin-spin interactions are responsible for the core polarization, and because of the core polarization the spin gyromagnetic factors are quenched. By considering the core polarization effects, a satisfactory agreement is obtained for the computed ground state g K factor, which gives an intrinsic contribution to the magnetic moments. In order to assess the collective contribution to the magnetic moments, the rotational gyromagnetic factors g R have been also calculated within the cranking approximation using the single particle wave function of the axially symmetric Woods-Saxon potential. For the ground-state magnetic moments of odd-proton 155-165Ho nuclei, a good description of the experimental data is obtained with an accuracy of 0.01-0.1 μ N. From systematic trends, the quenching spin gyromagnetic factor, g K factor and magnetic moment have also been theoretically predicted for 167,169Ho where there is no existing experimental data. Supported by Scientific and Technological Research Council of Turkey (TUBITAK) (115F564)

Resonances in odd-odd 182Ta

NASA Astrophysics Data System (ADS)

Brits, C. P.; Wiedeking, M.; Bello Garrote, F. L.; Bleuel, D. L.; Giacoppo, F.; Görgen, A.; Guttormsen, M.; Hadynska-Klek, K.; Hagen, T. W.; Ingeberg, V. W.; Kheswa, B. V.; Klintefjord, M.; Larsen, A. C.; Malatji, K. L.; Nyhus, H. T.; Papka, P.; Renstrøm, T.; Rose, S.; Sahin, E.; Siem, S.; Tveten, G. M.; Zeiser, F.

2017-09-01

Enhanced γ-decay on the tail of the giant electric dipole resonance, such as the scissors or pygmy resonances, can have significant impact on (n,γ) reaction rates. These rates are important input for modeling processes that take place in astrophysical environments and nuclear reactors. Recent results from the University of Oslo indicate the existence of a significant enhancement in the photon strength function for nuclei in the actinide region due to the scissors resonance. Further, the M1 strength distribution of the scissors resonances in rare earth nuclei has been studied extensively over the years. To investigate the evolution and persistence of the scissor resonance in other mass regions, an experiment was performed utilizing the NaI(Tl) γ-ray detector array (CACTUS) and silicon particle telescopes (SiRi) at the University of Oslo Cyclotron laboratory. Particle-γ coincidences from the 181Ta(d,p)182Ta and 181Ta(d,d')181Ta reactions were used to measure the nuclear level density and photon strength function of the well-deformed 181Ta and 182Ta systems, to investigate the existence of resonances below the neutron separation energy. Note to the reader: the title of this article has been corrected on September 19, 2017.

Effect of deformations on the compactness of odd-Z superheavy nuclei formed in cold and hot fusion reactions

NASA Astrophysics Data System (ADS)

Kaur, Gurjit; Sandhu, Kirandeep; Sharma, Manoj K.

2018-03-01

Using the extended fragmentation theory, the compactness of hot and cold fusion reactions is analyzed for odd-Z nuclei ranging Z = 105- 117. The calculations for the present work are carried out at T = 0MeV and ℓ = 0 ħ, as the temperature and angular momentum effects remain silent while addressing the orientation degree of freedom (i.e. compact angle configuration). In the hot fusion, 48Ca (spherical) + actinide (prolate) reaction, the non-equatorial compact (nec) shape is obtained for Z = 113 nucleus. On the other hand, Z > 113 nuclei favor equatorial compact (ec) configuration. The distribution of barrier height (VB) illustrate that the ec-shape is obtained when the magnitude of quadrupole deformation of the nucleus is higher than the hexadecupole deformation. In other words, negligible or small -ve β4-deformations support ec configurations. On the other hand, large (+ve) magnitude of the β4-deformation suggests that the configuration appears for compact angle θc < 90 °, leading to nec structure. Similar deformation effects are observed for Bi-induced reactions, in which not belly-to-belly compact (nbbc) configurations are seen at θc = 42 °. In addition to the effect of β2 and β4-deformations, the exclusive role of octupole deformations (β3) is also analyzed. The β3-deformations do not follow the reflection symmetry as that of β2 and β4, leading to the possible occurrence of compact configuration within 0° to 180° angular range.

Towards high-resolution laser ionization spectroscopy of the heaviest elements in supersonic gas jet expansion

PubMed Central

Ferrer, R.; Barzakh, A.; Bastin, B.; Beerwerth, R.; Block, M.; Creemers, P.; Grawe, H.; de Groote, R.; Delahaye, P.; Fléchard, X.; Franchoo, S.; Fritzsche, S.; Gaffney, L. P.; Ghys, L.; Gins, W.; Granados, C.; Heinke, R.; Hijazi, L.; Huyse, M.; Kron, T.; Kudryavtsev, Yu.; Laatiaoui, M.; Lecesne, N.; Loiselet, M.; Lutton, F.; Moore, I. D.; Martínez, Y.; Mogilevskiy, E.; Naubereit, P.; Piot, J.; Raeder, S.; Rothe, S.; Savajols, H.; Sels, S.; Sonnenschein, V.; Thomas, J-C; Traykov, E.; Van Beveren, C.; Van den Bergh, P.; Van Duppen, P.; Wendt, K.; Zadvornaya, A.

2017-01-01

Resonant laser ionization and spectroscopy are widely used techniques at radioactive ion beam facilities to produce pure beams of exotic nuclei and measure the shape, size, spin and electromagnetic multipole moments of these nuclei. However, in such measurements it is difficult to combine a high efficiency with a high spectral resolution. Here we demonstrate the on-line application of atomic laser ionization spectroscopy in a supersonic gas jet, a technique suited for high-precision studies of the ground- and isomeric-state properties of nuclei located at the extremes of stability. The technique is characterized in a measurement on actinium isotopes around the N=126 neutron shell closure. A significant improvement in the spectral resolution by more than one order of magnitude is achieved in these experiments without loss in efficiency. PMID:28224987

A new equation of state Based on Nuclear Statistical Equilibrium for Core-Collapse Simulations

NASA Astrophysics Data System (ADS)

Furusawa, Shun; Yamada, Shoichi; Sumiyoshi, Kohsuke; Suzuki, Hideyuki

2012-09-01

We calculate a new equation of state for baryons at sub-nuclear densities for the use in core-collapse simulations of massive stars. The formulation is the nuclear statistical equilibrium description and the liquid drop approximation of nuclei. The model free energy to minimize is calculated by relativistic mean field theory for nucleons and the mass formula for nuclei with atomic number up to ~ 1000. We have also taken into account the pasta phase. We find that the free energy and other thermodynamical quantities are not very different from those given in the standard EOSs that adopt the single nucleus approximation. On the other hand, the average mass is systematically different, which may have an important effect on the rates of electron captures and coherent neutrino scatterings on nuclei in supernova cores.

Lifetimes of excited states in triaxially deformed 107Tc and 109,111,113Rh

NASA Astrophysics Data System (ADS)

Hagen, T. W.; Görgen, A.; Korten, W.; Grente, L.; Salsac, M.-D.; Farget, F.; Braunroth, T.; Bruyneel, B.; Celikovic, I.; Clément, E.; de France, G.; Delaune, O.; Dewald, A.; Dijon, A.; Hackstein, M.; Jacquot, B.; Litzinger, J.; Ljungvall, J.; Louchart, C.; Michelagnoli, C.; Napoli, D. R.; Recchia, F.; Rother, W.; Sahin, E.; Siem, S.; Sulignano, B.; Theisen, Ch.; Valiente-Dobon, J. J.

2018-03-01

Lifetimes of excited states in 107Tc, 109Rh, 111Rh, and 113Rh were measured at GANIL using the Recoil-Distance Doppler Shift method. The neutron-rich nuclei were produced in fission reactions in inverse kinematics with a 238U beam impinging on a 9Be target. Fission fragments were identified event-by-event in the ray-tracing spectrometer VAMOS++ and correlated with prompt γ rays observed around the target position with the EXOGAM Ge detector array. Several lifetimes were obtained for states in the positive-parity yrast bands in the four nuclei and compared to triaxial particle-rotor calculations. The results clarify the configuration for the strongest positive-parity band in 107Tc and suggest a gradual increase of triaxial deformation with atomic number Z, reaching almost maximum triaxiality for the neutron-rich Rh nuclei.

A New Accelerator-Based Mass Spectrometry.

ERIC Educational Resources Information Center

Gove, H. E.

1983-01-01

Tandem electrostatic accelerators produce beams of positive ions which are used to penetrate atomic nuclei in a target, inducing nuclear reactions whose study elucidates varied properties of the nucleus. Uses of the system, which acts like a mass spectrometer, are discussed. These include radiocarbon dating measurements. (JN)

11.2 Solar Neutrinos

NASA Astrophysics Data System (ADS)

Nakahata, Masayuki

This document is part of Subvolume A `Theory and Experiments' of Volume 21 `Elementary Particles' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It contains of the Chapter `11 Experimental Results on Neutrino Masses and Mixings' the Section `11.2 Solar Neutrinos' with the content:

Nuclear Quantum Effects in Water at the Triple Point: Using Theory as a Link Between Experiments.

PubMed

Cheng, Bingqing; Behler, Jörg; Ceriotti, Michele

2016-06-16

One of the most prominent consequences of the quantum nature of light atomic nuclei is that their kinetic energy does not follow a Maxwell-Boltzmann distribution. Deep inelastic neutron scattering (DINS) experiments can measure this effect. Thus, the nuclear quantum kinetic energy can be probed directly in both ordered and disordered samples. However, the relation between the quantum kinetic energy and the atomic environment is a very indirect one, and cross-validation with theoretical modeling is therefore urgently needed. Here, we use state of the art path integral molecular dynamics techniques to compute the kinetic energy of hydrogen and oxygen nuclei in liquid, solid, and gas-phase water close to the triple point, comparing three different interatomic potentials and validating our results against equilibrium isotope fractionation measurements. We will then show how accurate simulations can draw a link between extremely precise fractionation experiments and DINS, therefore establishing a reliable benchmark for future measurements and providing key insights to increase further the accuracy of interatomic potentials for water.

Molecular processes in astrophysics: Calculations of hydrogen + hydrogen gas excitation, de-excitation, and cooling

NASA Astrophysics Data System (ADS)

Kelley, Matthew Thomas

The implications of H+H2 cooling in astrophysics is important to several applications. One of the most significant and pure applications is its role in cooling in the early universe. Other applications would include molecular dynamics in nebulae and their collapse into stars and astrophysical shocks. Shortly after the big bang, the universe was a hot primordial gas of photons, electrons, and nuclei among other ingredients. By far the most dominant nuclei in the early universe was hydrogen. In fact, in the early universe the matter density was 90 percent hydrogen and only 10 percent helium with small amounts of lithium and deuterium. In order for structure to form in the universe, this primordial gas must form atoms and cool. One of the significant cooling mechanisms is the collision of neutral atomic hydrogen with a neutral diatomic hydrogen molecule. This work performs calculations to determine collisional cooling rates of hydrogen using two potential surfaces.

Coherent Patterns in Nuclei and in Financial Markets

NASA Astrophysics Data System (ADS)

DroŻdŻ, S.; Kwapień, J.; Speth, J.

2010-07-01

In the area of traditional physics the atomic nucleus belongs to the most complex systems. It involves essentially all elements that characterize complexity including the most distinctive one whose essence is a permanent coexistence of coherent patterns and of randomness. From a more interdisciplinary perspective, these are the financial markets that represent an extreme complexity. Here, based on the matrix formalism, we set some parallels between several characteristics of complexity in the above two systems. We, in particular, refer to the concept—historically originating from nuclear physics considerations—of the random matrix theory and demonstrate its utility in quantifying characteristics of the coexistence of chaos and collectivity also for the financial markets. In this later case we show examples that illustrate mapping of the matrix formulation into the concepts originating from the graph theory. Finally, attention is drawn to some novel aspects of the financial coherence which opens room for speculation if analogous effects can be detected in the atomic nuclei or in other strongly interacting Fermi systems.

Production of twin /Λ-hypernuclei from Ξ- hyperon capture at rest

NASA Astrophysics Data System (ADS)

Ichikawa, A.; Ahn, J. K.; Akikawa, H.; Aoki, S.; Arai, K.; Bahk, S. Y.; Baik, K. M.; Bassalleck, B.; Chung, J. H.; Chung, M. S.; Hoshino, K.; Ieiri, M.; Imai, K.; Iwata, Y. H.; Iwata, Y. S.; Kanda, H.; Kaneko, M.; Kawai, T.; Kim, C. O.; Kim, J. Y.; Kim, S. J.; Kim, S. H.; Kondo, Y.; Kouketsu, T.; Lee, Y. L.; McNabb, J. W. C.; Mitsuhara, M.; Nagase, Y.; Nagoshi, C.; Nakazawa, K.; Noumi, H.; Ogawa, S.; Okabe, H.; Oyama, K.; Park, H. M.; Park, I. G.; Parker, J.; Ra, Y. S.; Rhee, J. T.; Rusek, A.; Shibuya, H.; Sim, K. S.; Saha, P. K.; Seki, D.; Sekimoto, M.; Song, J. S.; Takahashi, H.; Takahashi, T.; Takeutchi, F.; Tanaka, H.; Tanida, K.; Tojo, J.; Torii, H.; Torikai, S.; Ushida, N.; Yamamoto, K.; Yasuda, N.; Yang, J. T.; Yoon, C. J.; Yoon, C. S.; Yosoi, M.; Yoshida, T.; Zhu, L.

2001-02-01

A hybrid emulsion experiment was carried out to study double-strangeness nuclei produced via Ξ- hyperon capture at rest with the expectation of ten times larger statistics than previous experiments. We have analyzed 5% of the total emulsion and found one ``twin-hypernuclei'' event involving the emission of two single-/Λ hypernuclei and a nuclear fragment from a Ξ- hyperon stopping point. The event is interpreted as the decay of a Ξ-+14N atomic system to 5ΛHe+5ΛHe+4He+neutron. The species of the Ξ--atom and the fragmentation products are uniquely identified for the first time for twin-hypernuclei events. Combined with the results from a past hybrid-emulsion experiment, one double-/Λ hypernucleus and three twin-hypernuclei events have been found from Ξ- captures on light emulsion nuclei. The ratio of the detected rate of double-/Λ hypernuclei to that of twin-hypernuclei is compared with theoretical estimates.

Space shuttle exhaust cloud properties

NASA Technical Reports Server (NTRS)

Anderson, B. J.; Keller, V. W.

1983-01-01

A data base describing the properties of the exhaust cloud produced by the launch of the Space Transportation System and the acidic fallout observed after each of the first four launches was assembled from a series of ground and aircraft based measurements made during the launches of STS 2, 3, and 4. Additional data were obtained from ground-based measurements during firings of the 6.4 percent model of the Solid Rocket Booster at the Marshall Center. Analysis indicates that the acidic fallout is produced by atomization of the deluge water spray by the rocket exhaust on the pad followed by rapid scavening of hydrogen chloride gas aluminum oxide particles from the Solid Rocket Boosters. The atomized spray is carried aloft by updrafts created by the hot exhaust and deposited down wind. Aircraft measurements in the STS-3 ground cloud showed an insignificant number of ice nuclei. Although no measurements were made in the column cloud, the possibility of inadvertent weather modification caused by the interaction of ice nuclei with natural clouds appears remote.

Nickel-63 production in copper samples exposed to the Hiroshima atomic bomb: estimation based on an excitation function obtained by neutron irradiation experiments.

PubMed

Takamiya, K; Imanaka, T; Ota, Y; Akamine, M; Shibata, S; Shibata, T; Ito, Y; Imamura, M; Uwamino, Y; Nogawa, N; Baba, M; Iwasaki, S; Matsuyama, S

2008-07-01

The upper and lower limits of the excitation function of the (63)Cu(n,p)(63)Ni reaction were experimentally determined, and the number of (63)Ni nuclei produced in copper samples exposed to atomic bomb neutrons in Hiroshima was estimated by using the experimental excitation functions and the neutron fluences given in the DS02 dosimetry system. The estimated number of (63)Ni nuclei was compared with that measured and with that calculated using the DS02 dosimetry system and the corresponding ENDF/B-VI cross section. In comparison with DS02, there is about a 60% maximum difference in (63)Ni production at the hypocenter when the experimental upper cross section values are used. The difference becomes smaller at greater distances from the hypocenter and decreases, for example, to less than 30 and 5% when using the upper and lower experimental cross sections at 1,000 m, respectively.

Development of methods for calculating basic features of the nuclear contribution to single event upsets under the effect of protons of moderately high energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chechenin, N. G., E-mail: chechenin@sinp.msu.ru; Chuvilskaya, T. V.; Shirokova, A. A.

2015-10-15

As a continuation and a development of previous studies of our group that were devoted to the investigation of nuclear reactions induced by protons of moderately high energy (between 10 and 400 MeV) in silicon, aluminum, and tungsten atoms, the results obtained by exploring nuclear reactions on atoms of copper, which is among the most important components in materials for contact pads and pathways in modern and future ultralarge-scale integration circuits, especially in three-dimensional topology, are reported in the present article. The nuclear reactions in question lead to the formation of the mass and charge spectra of recoil nuclei rangingmore » fromheavy target nuclei down to helium and hydrogen. The kineticenergy spectra of reaction products are calculated. The results of the calculations based on the procedure developed by our group are compared with the results of calculations and experiments performed by other authors.« less

Quantum Chemical Topology: Knowledgeable atoms in peptides

NASA Astrophysics Data System (ADS)

Popelier, Paul L. A.

2012-06-01

The need to improve atomistic biomolecular force fields remains acute. Fortunately, the abundance of contemporary computing power enables an overhaul of the architecture of current force fields, which typically base their electrostatics on fixed atomic partial charges. We discuss the principles behind the electrostatics of a more realistic force field under construction, called QCTFF. At the heart of QCTFF lies the so-called topological atom, which is a malleable box, whose shape and electrostatics changes in response to a changing environment. This response is captured by a machine learning method called Kriging. Kriging directly predicts each multipole moment of a given atom (i.e. the output) from the coordinates of the nuclei surrounding this atom (i.e. the input). This procedure yields accurate interatomic electrostatic energies, which form the basis for future-proof progress in force field design.

Material Science

NASA Image and Video Library

2003-02-09

Materials with a smaller mean atomic mass, such as lithium (Li) hydride and polyethylene, make the best radiation shields for astronauts. The materials have a higher density of nuclei and are better able to block incoming radiation. Also, they tend to produce fewer and less dangerous secondary particles after impact with incoming radiation.

The Gibbs free energy of homogeneous nucleation: From atomistic nuclei to the planar limit.

PubMed

Cheng, Bingqing; Tribello, Gareth A; Ceriotti, Michele

2017-09-14

In this paper we discuss how the information contained in atomistic simulations of homogeneous nucleation should be used when fitting the parameters in macroscopic nucleation models. We show how the number of solid and liquid atoms in such simulations can be determined unambiguously by using a Gibbs dividing surface and how the free energy as a function of the number of solid atoms in the nucleus can thus be extracted. We then show that the parameters (the chemical potential, the interfacial free energy, and a Tolman correction) of a model based on classical nucleation theory can be fitted using the information contained in these free-energy profiles but that the parameters in such models are highly correlated. This correlation is unfortunate as it ensures that small errors in the computed free energy surface can give rise to large errors in the extrapolated properties of the fitted model. To resolve this problem we thus propose a method for fitting macroscopic nucleation models that uses simulations of planar interfaces and simulations of three-dimensional nuclei in tandem. We show that when the chemical potentials and the interface energy are pinned to their planar-interface values, more precise estimates for the Tolman length are obtained. Extrapolating the free energy profile obtained from small simulation boxes to larger nuclei is thus more reliable.

Preliminary results for salt aerosol production intended for marine cloud brightening, using effervescent spray atomization

PubMed Central

Cooper, Gary; Foster, Jack; Galbraith, Lee; Jain, Sudhanshu; Neukermans, Armand; Ormond, Bob

2014-01-01

The large-scale production of vast numbers of suitable salt nuclei and their upward launch is one of the main technological barriers to the experimental testing of marine cloud brightening (MCB). Very promising, though not definitive, results have been obtained using an adapted version of effervescent spray atomization. The process is simple, robust and inexpensive. This form of effervescent spraying uses only pressurized water and air sprayed from small nozzles to obtain very fine distributions. While it is far from optimized, and may not be the best method if full deployment is ever desired, we believe that even in its present form the process would lend itself well to preliminary field test investigations of MCB. Measurements obtained using standard aerosol instrumentation show approximately lognormal distributions of salt nuclei with median diameters of approximately 65 nm and geometric standard deviations slightly less than 2. However, these measurements are not in agreement with those based on scanning electron microscopy imaging of collected particles, an observation that has not yet been explained. Assuming the above distribution, 1015 particles per second could be made with 21 kW of spray power, using approximately 200 nozzles. It is envisioned that existing snow making equipment can be adapted to launch the nuclei 60–100 m into the air, requiring approximately 20 kW of additional power. PMID:25404673

Nuclear quantum shape-phase transitions in odd-mass systems

NASA Astrophysics Data System (ADS)

Quan, S.; Li, Z. P.; Vretenar, D.; Meng, J.

2018-03-01

Microscopic signatures of nuclear ground-state shape-phase transitions in odd-mass Eu isotopes are explored starting from excitation spectra and collective wave functions obtained by diagonalization of a core-quasiparticle coupling Hamiltonian based on energy density functionals. As functions of the physical control parameter—the number of nucleons—theoretical low-energy spectra, two-neutron separation energies, charge isotope shifts, spectroscopic quadrupole moments, and E 2 reduced transition matrix elements accurately reproduce available data and exhibit more-pronounced discontinuities at neutron number N =90 compared with the adjacent even-even Sm and Gd isotopes. The enhancement of the first-order quantum phase transition in odd-mass systems can be attributed to a shape polarization effect of the unpaired proton which, at the critical neutron number, starts predominantly coupling to Gd core nuclei that are characterized by larger quadrupole deformation and weaker proton pairing correlations compared with the corresponding Sm isotopes.

A computational NMR study on zigzag aluminum nitride nanotubes

NASA Astrophysics Data System (ADS)

Bodaghi, Ali; Mirzaei, Mahmoud; Seif, Ahmad; Giahi, Masoud

2008-12-01

A computational nuclear magnetic resonance (NMR) study is performed to investigate the electronic structure properties of the single-walled zigzag aluminum nitride nanotubes (AlNNTs). The chemical-shielding (CS) tensors are calculated at the sites of Al-27 and N-15 nuclei in three structural forms of AlNNT including H-saturated, Al-terminated, and N-terminated ones. The structural forms are firstly optimized and then the calculated CS tensors in the optimized structures are converted to chemical-shielding isotropic (CSI) and chemical-shielding anisotropic (CSA) parameters. The calculated parameters reveal that various Al-27 and N-15 nuclei are divided into some layers with equivalent electrostatic properties; furthermore, Al and N can act as Lewis base and acid, respectively. In the Al-terminated and N-terminated forms of AlNNT, in which one mouth of the nanotube is terminated by aluminum and nitrogen nuclei, respectively, just the CS tensors of the nearest nuclei to the mouth of the nanotube are significantly changed due to removal of saturating hydrogen atoms. Density functional theory (DFT) calculations are performed using GAUSSIAN 98 package of program.

First lattice QCD study of the gluonic structure of light nuclei

NASA Astrophysics Data System (ADS)

Winter, Frank; Detmold, William; Gambhir, Arjun S.; Orginos, Kostas; Savage, Martin J.; Shanahan, Phiala E.; Wagman, Michael L.; Nplqcd Collaboration

2017-11-01

The role of gluons in the structure of the nucleon and light nuclei is investigated using lattice quantum chromodynamics (QCD) calculations. The first moment of the unpolarized gluon distribution is studied in nuclei up to atomic number A =3 at quark masses corresponding to pion masses of mπ˜450 and 806 MeV. Nuclear modification of this quantity defines a gluonic analogue of the EMC effect and is constrained to be less than ˜10 % in these nuclei. This is consistent with expectations from phenomenological quark distributions and the momentum sum rule. In the deuteron, the combination of gluon distributions corresponding to the b1 structure function is found to have a small first moment compared with the corresponding momentum fraction. The first moment of the gluon transversity structure function is also investigated in the spin-1 deuteron, where a nonzero signal is observed at mπ˜806 MeV . This is the first indication of gluon contributions to nuclear structure that can not be associated with an individual nucleon.

First lattice QCD study of the gluonic structure of light nuclei

DOE PAGES

Winter, Frank; Detmold, William; Gambhir, Arjun S.; ...

2017-11-28

The role of gluons in the structure of the nucleon and light nuclei is investigated using lattice quantum chromodynamics (QCD) calculations. The first moment of the unpolarised gluon distribution is studied in nuclei up to atomic numbermore » $A=3$ at quark masses corresponding to pion masses of $$m_\\pi\\sim 450$$ and $806$ MeV. Nuclear modification of this quantity defines a gluonic analogue of the EMC effect and is constrained to be less than $$\\sim 10$$% in these nuclei. This is consistent with expectations from phenomenological quark distributions and the momentum sum rule. In the deuteron, the combination of gluon distributions corresponding to the $$b_1$$ structure function is found to have a small first moment compared with the corresponding momentum fraction. The first moment of the gluon transversity structure function is also investigated in the spin-1 deuteron, where a non-zero signal is observed at $$m_\\pi \\sim 806$$ MeV. In conclusion, this is the first indication of gluon contributions to nuclear structure that can not be associated with an individual nucleon.« less

An Adaptive QSE-reduced Nuclear Reaction Network for Silicon Burning

NASA Astrophysics Data System (ADS)

Parete-Koon, Suzanne; Hix, William Raphael; Thielemann, Friedrich-Karl

2010-02-01

The nuclei of the ``iron peak'' are formed late in the evolution of massive stars and during supernovae. Silicon burning during these events is responsible for the production of a wide range of nuclei with atomic mass numbers from 28 to 64. The large number of nuclei involved make accurate modeling of silicon burning computationally expensive. Examination of the physics of silicon burning reveals that the nuclear evolution is dominated by large groups of nuclei in mutual equilibrium. We present an improvement on our hybrid equilibrium-network scheme that takes advantage of this quasi-equilibrium (QSE) to reduce the number of independent variables calculated. Because the membership and number of these groups vary as the temperature, density and electron faction change, achieving maximal efficiency requires dynamic adjustment of group number and membership. The resultant QSE-reduced network is up to 20 times faster than the full network it replaces without significant loss of accuracy. These reductions in computational cost and the number of species evolved make QSE-reduced networks well suited for inclusion within hydrodynamic simulations, particularly in multi-dimensional applications. )

A new baryonic equation of state at sub-nuclear densities for core-collapse simulations

NASA Astrophysics Data System (ADS)

Furusawa, Shun; Yamada, Shoichi; Sumiyoshi, Kohsuke; Suzuki, Hideyuki

2012-11-01

We construct a new equation of state for baryons at sub-nuclear densities for the use in core-collapse simulations of massive stars. The formulation is based on the nuclear statistical equilibrium description and the liquid drop approximation of nuclei. The model free energy to minimize is calculated by using relativistic mean field theory for nucleons and the mass formula for nuclei with atomic number up to ~ 1000. We have also taken into account the pasta phase. We find that the free energy and other thermodynamical quantities are not very different from those given in the standard EOSs that adopt the single nucleus approximation. On the other hand, the average mass is systematically different, which may have an important effect to the rates of electron captures and coherent neutrino scatterings on nuclei in supernova cores. It is also interesting that the root mean square of the mass number is not very different from the average mass number, since the former is important for the evaluation of coherent scattering rates on nuclei but has been unavailable so far.

Search for P-ODD asymmetry in the radiative cross-section of the interaction of neutrons with lead nuclei

NASA Astrophysics Data System (ADS)

Gledenov, Yu. M.; Nesvizhevsky, V. V.; Sedyshev, P. V.; Shul'gina, E. V.; Vesna, V. A.

2014-03-01

The P-odd effect in the radiation cross section of capture of longitudinally polarized neutrons in a sample of natural lead is measured. The experiment was performed at PF1B facility at the Institut Max von Laue-Paul Langevin. The neutron polarization P n was 92%, the total flux of polarized neutrons was ˜3 × 1010 n/s, and the mean neutron wavelength was λ = 4.7 Å. Taking into account "0-test" we estimated the asymmetry: a γ(natPb) = (2.3 ± 3.5) × 10-7, i.e., α γ ≤ 8.1 × 10-7 at 90% confidence level.

New, simplified, interpolation method for estimation of microscopic nuclear masses based on the p-factor, P = N/sub P/N/sub N//(N/sub p/+N/sub n/)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haustein, P.E.; Brenner, D.S.; Casten, R.F.

1987-12-10

A new semi-empirical method, based on the use of the P-factor (P = N/sub p/N/sub n//(N/sub p/+N/sub n/)), is shown to simplify significantly the systematics of atomic masses. Its uses is illustrated for actinide nuclei where complicated patterns of mass systematics seen in traditional plots versus Z, N, or isospin are consolidated and transformed into linear ones extending over long isotopic and isotonic sequences. The linearization of the systematics by this procedure provides a simple basis for mass prediction. For many unmeasured nuclei beyond the known mass surface, the P-factor method operates by interpolation among data for known nuclei rathermore » than by extrapolation, as is common in other mass models.« less

Nuclear inertia and the decay modes of superheavy nuclei

NASA Astrophysics Data System (ADS)

Poenaru, D. N.; Gherghescu, R. A.; Greiner, Walter

2013-10-01

Superheavy nuclei produced up to now decay mainly by α emission and spontaneous fission. For atomic numbers larger than 121 cluster decay has a good chance to compete. While calculated α decay half-lives are in agreement with experimental data within one order of magnitude and cluster decay experiments are also very well accounted for, the discrepancy between theory and experiment can be as high as ten orders of magnitude for spontaneous fission. We analyze some ways of improving the accuracy: using a semiempirical formula for α decay and changing the parameters of analytical superasymmetric fission and of the universal curve for cluster decay. For spontaneous fission we act on nuclear dynamics based on potential barriers computed by the macroscopic-microscopic method and employing various nuclear inertia variation laws. Applications are illustrated for 284Cn and Z = 118-124 even-even parent nuclei. Communicated by Steffen Bass

CRPropa 2.0 - A public framework for propagating high energy nuclei, secondary gamma rays and neutrinos

NASA Astrophysics Data System (ADS)

Kampert, Karl-Heinz; Kulbartz, Jörg; Maccione, Luca; Nierstenhoefer, Nils; Schiffer, Peter; Sigl, Günter; van Vliet, Arjen René

2013-02-01

Version 2.0 of CRPropa [CRPropa is published under the 3rd version of the GNU General Public License (GPLv3). It is available, together with a detailed documentation of the code, at https://crpropa.desy.de.] is public software to model the extra-galactic propagation of ultra-high energy nuclei of atomic number Z⩽26 through structured magnetic fields and ambient photon backgrounds taking into account all relevant particle interactions. CRPropa covers the energy range 7×1016

Statistical Analysis For Nucleus/Nucleus Collisions

NASA Technical Reports Server (NTRS)

Mcguire, Stephen C.

1989-01-01

Report describes use of several statistical techniques to charactertize angular distributions of secondary particles emitted in collisions of atomic nuclei in energy range of 24 to 61 GeV per nucleon. Purpose of statistical analysis to determine correlations between intensities of emitted particles and angles comfirming existence of quark/gluon plasma.

Students' use of atomic and molecular models in learning chemistry

NASA Astrophysics Data System (ADS)

O'Connor, Eileen Ann

1997-09-01

The objective of this study was to investigate the development of introductory college chemistry students' use of atomic and molecular models to explain physical and chemical phenomena. The study was conducted during the first semester of the course at a University and College II. Public institution (Carnegie Commission of Higher Education, 1973). Students' use of models was observed during one-on-one interviews conducted over the course of the semester. The approach to introductory chemistry emphasized models. Students were exposed to over two-hundred and fifty atomic and molecular models during lectures, were assigned text readings that used over a thousand models, and worked interactively with dozens of models on the computer. These models illustrated various features of the spatial organization of valence electrons and nuclei in atoms and molecules. Despite extensive exposure to models in lectures, in textbook, and in computer-based activities, the students in the study based their explanation in large part on a simple Bohr model (electrons arranged in concentric circles around the nuclei)--a model that had not been introduced in the course. Students used visual information from their models to construct their explanation, while overlooking inter-atomic and intra-molecular forces which are not represented explicitly in the models. In addition, students often explained phenomena by adding separate information about the topic without either integrating or logically relating this information into a cohesive explanation. The results of the study demonstrate that despite the extensive use of models in chemistry instruction, students do not necessarily apply them appropriately in explaining chemical and physical phenomena. The results of this study suggest that for the power of models as aids to learning to be more fully realized, chemistry professors must give more attention to the selection, use, integration, and limitations of models in their instruction.

Ab initio simulation of particle momentum distributions in high-pressure water

NASA Astrophysics Data System (ADS)

Ceriotti, M.

2014-12-01

Applying pressure to water reduces the average oxygen-oxygen distance, and facilitates the delocalisation of protons along the hydrogen bond. This pressure-induced delocalisation is further enhanced by the quantum nature of hydrogen nuclei, which is very significant even well above room temperature. Here we will evaluate the quantum kinetic energy and the particle momentum distribution of hydrogen and oxygen nuclei in water at extreme pressure, using ab initio path integral molecular dynamics. We will show that (transient) dissociation of water molecules induce measurable changes in the kinetic energy hydrogen atoms, although current deep inelastic scattering experiments are probably unable to capture the heterogeneity of the sample.

Experimental level densities of atomic nuclei

DOE PAGES

Guttormsen, M.; Aiche, M.; Bello Garrote, F. L.; ...

2015-12-23

It is almost 80 years since Hans Bethe described the level density as a non-interacting gas of protons and neutrons. In all these years, experimental data were interpreted within this picture of a fermionic gas. However, the renewed interest of measuring level density using various techniques calls for a revision of this description. In particular, the wealth of nuclear level densities measured with the Oslo method favors the constant-temperature level density over the Fermi-gas picture. Furthermore, trom the basis of experimental data, we demonstrate that nuclei exhibit a constant-temperature level density behavior for all mass regions and at least upmore » to the neutron threshold.« less

Hyperfine structure investigations for the odd-parity configuration system in atomic holmium

NASA Astrophysics Data System (ADS)

Stefanska, D.; Furmann, B.

2018-02-01

In this work new experimental results of the hyperfine structure (hfs) in the holmium atom are reported, concerning the odd-parity level system. Investigations were performed by the method of laser induced fluorescence in a hollow cathode discharge lamp on 97 spectral lines in the visible part of the spectrum. Hyperfine structure constants: magnetic dipole - A and electric quadrupole - B for 40 levels were determined for the first time; for another 21 levels the hfs constants available in the literature were remeasured. Results for the A constants can be viewed as fully reliable; for B constants further possibilities of improving the accuracy are considered.

Friction and work function oscillatory behavior for an even and odd number of layers in polycrystalline MoS 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lavini, Francesco; Calò, Annalisa; Gao, Yang

We report on a new oscillatory behavior of nanoscopic friction in continuous polycrystalline MoS 2 films for an odd and even number of atomic layers, related to the different in-plane polarization of crystalline grains and different capability of absorbing charged molecules.

Friction and work function oscillatory behavior for an even and odd number of layers in polycrystalline MoS 2

DOE PAGES

Lavini, Francesco; Calò, Annalisa; Gao, Yang; ...

2018-01-01

We report on a new oscillatory behavior of nanoscopic friction in continuous polycrystalline MoS 2 films for an odd and even number of atomic layers, related to the different in-plane polarization of crystalline grains and different capability of absorbing charged molecules.

Local order parameters for use in driving homogeneous ice nucleation with all-atom models of water

NASA Astrophysics Data System (ADS)

Reinhardt, Aleks; Doye, Jonathan P. K.; Noya, Eva G.; Vega, Carlos

2012-11-01

We present a local order parameter based on the standard Steinhardt-Ten Wolde approach that is capable both of tracking and of driving homogeneous ice nucleation in simulations of all-atom models of water. We demonstrate that it is capable of forcing the growth of ice nuclei in supercooled liquid water simulated using the TIP4P/2005 model using over-biassed umbrella sampling Monte Carlo simulations. However, even with such an order parameter, the dynamics of ice growth in deeply supercooled liquid water in all-atom models of water are shown to be very slow, and so the computation of free energy landscapes and nucleation rates remains extremely challenging.

Recent trends in precision measurements of atomic and nuclear properties with lasers and ion traps

NASA Astrophysics Data System (ADS)

Block, Michael

2017-11-01

The X. international workshop on "Application of Lasers and Storage Devices in Atomic Nuclei Research" took place in Poznan in May 2016. It addressed the latest experimental and theoretical achievements in laser and ion trap-based investigations of radionuclides, highly charged ions and antiprotons. The precise determination of atomic and nuclear properties provides a stringent benchmark for theoretical models and eventually leads to a better understanding of the underlying fundamental interactions and symmetries. This article addresses some general trends in this field and highlights select recent achievements presented at the workshop. Many of these are covered in more detail within the individual contributions to this special issue of Hyperfine Interactions.

LAD Prize Talk: Lab Astro and the Origins of the Chemical Elements

NASA Astrophysics Data System (ADS)

Lawler, James E.

2017-06-01

Only a few of the lightest or primordial nuclei were made just after the Big Bang. Other light nuclei up to the Fe-group are made by fusion in stars. Heavier nuclei are made primarily via r(apid)-process and s(low)-process n(eutron)-capture events. Although the s-process n-capture is fairly well understood, the r-process n-capture events remain poorly understood. The relative role of Core Collapse SNe and n-star mergers will likely be understood in the next few decades. I will discuss recent studies of old Metal-Poor stars that are revealing some new details of nucleosynthesis. This progress is due to the availability of high resolution spectra from large ground based telescopes, access to the UV via HST, and better laboratory data. Our laboratory astrophysics program has focused primarily on the measurement of transition probabilities by combining radiative lifetimes with emission branching fractions. The use of Time Resolved Laser Induced Fluorescence (TRLIF) to measure radiative lifetimes in metallic atoms and ions provides an absolute scale for transition probabilities accurate to a few percent [e.g. 1]. The development and application of TRLIF to neutral and ionized atoms of nearly all elements is due to a simple, versatile, and reliable atom/ion beam source based on a hollow cathode discharge [2, 3]. Fourier transform spectrometers (FTSs) are essential in the measurement of emission branching fractions for atoms and ions with dense spectra such as the rare earths [e.g. 4, 5]. A 3 m focal length echelle spectrometer is important to the measurement of weak branches which might otherwise be obscured by multiplex noise in FTS data [6, 7]. References: [1] E. A. Den Hartog et al., ApJS 194: 35 (2011). [2] D. W. Duquette et al., Phys. Rev. A24, 2847 (1981). [3] S. Salih & J. E. Lawler, Phys. Rev. A29, 3753, (1983). [4] J. W. Brault, J. Opt. Soc. Am. 66, 1081 (1976). [5] J. E. Lawler et al., ApJS 182, 51 (2009). [6] M. P. Wood & J. E. Lawler, Appl. Opt. 51, 8407 (2012). [7] C. Sneden et al., ApJ 817:53 (2016).

Architecture of Pd-Au bimetallic nanoparticles in sodium bis(2-ethylhexyl)sulfosuccinate reverse micelles as investigated by X-ray absorption spectroscopy.

PubMed

Chen, Ching-Hsiang; Sarma, Loka Subramanyam; Chen, Jium-Ming; Shih, Shou-Chu; Wang, Guo-Rung; Liu, Din-Goa; Tang, Mau-Tsu; Lee, Jyh-Fu; Hwang, Bing-Joe

2007-09-01

In this study, we demonstrate the unique application of X-ray absorption spectroscopy (XAS) as a fundamental characterization tool to help in designing and controlling the architecture of Pd-Au bimetallic nanoparticles within a water-in-oil microemulsion system of water/sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/n-heptane. Structural insights obtained from the in situ XAS measurements recorded at each step during the formation process revealed that Pd-Au bimetallic clusters with various Pd-Au atomic stackings are formed by properly performing hydrazine reduction and redox transmetalation reactions sequentially within water-in-oil microemulsions. A structural model is provided to explain reasonably each reaction step and to give detailed insight into the nucleation and growth mechanism of Pd-Au bimetallic clusters. The combination of in situ XAS analysis at both the Pd K-edge and the Au L(III)-edge and UV-vis absorption spectral features confirms that the formation of Pd-Au bimetallic clusters follows a (Pd(nuclei)-Au(stack))-Pd(surf) stacking. This result further implies that the thickness of Au(stack) and Pd(surf) layers may be modulated by varying the dosage of the Au precursor and hydrazine, respectively. In addition, a bimetallic (Pd-Au)(alloy) nanocluster with a (Pd(nuclei)-Au(stack))-(Pd-Au(alloy))(surf) stacking was also designed and synthesized in order to check the feasibility of Pd(surf) layer modification. The result reveals that the Pd(surf) layer of the stacked (Pd(nuclei)-Au)(stack) bimetallic clusters can be successfully modified to form a (Au-Pd alloy)(surf) layer by a co-reduction of Pd and Au ions by hydrazine. Further, we demonstrate the alloying extent or atomic distribution of Pd and Au in Pd-Au bimetallic nanoparticles from the derived XAS structural parameters. The complete XAS-based methodology, demonstrated here on the Pd-Au bimetallic system, can easily be extended to design and control the alloying extent or atomic distribution, atomic stacking, and electronic structure to construct many other types of bimetallic systems for interesting applications.

Studies of Heavy-Ion Reactions and Transuranic Nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schroeder, W. Udo

2016-07-28

Studies of heavy-ion reactions and transuranic nuclei performed by the University of Rochester Nuclear Science Research Group have been successful in furthering experimental systematics and theoretical understanding of the behavior of nuclear systems excited to their limits of stability. The theoretical results explain specifically the “boiling” and “vaporization” of atomic nuclei, but are more generally applicable to isolated, quantal many-particle systems which, under thermal or mechanical stresses, all disintegrate by evaporation, via surface cluster emission, or via fission-like processes. Accompanying experimental investigations by the group have demonstrated several new types of dynamical instability of nuclei: In central, “head-on” collisions, targetmore » nuclei exhibit limited ability to stop energetic projectile nuclei and to dissipate the imparted linear momentum. Substantial matter overlap (“neck”) between projectile and target nuclei, which is observed at elevated collision energies, can be stretched considerably and break at several places simultaneously. These results provide new testing grounds for microscopic theory of the cohesion of nuclear matter. This property has remained elusive, even though the elementary nucleon-nucleon forces are well known since some time. Technical R&D has resulted in a detailed characterization of a novel plastic material, which can now be used in the design of sensitive diagnostic systems for various types of radio-activity. Innovative application of powerful laser systems has produced intense, controllable sources of exotic particle radioactivity for nuclear investigations. Several students have received their Ph.D. degree in experimental nuclear science for their work on basic nuclear research or R&D projects.« less

Relativistic Normal Coupled-Cluster Theory for Accurate Determination of Electric Dipole Moments of Atoms: First Application to the 199Hg Atom

NASA Astrophysics Data System (ADS)

Sahoo, B. K.; Das, B. P.

2018-05-01

Recent relativistic coupled-cluster (RCC) calculations of electric dipole moments (EDMs) of diamagnetic atoms due to parity and time-reversal violating (P ,T -odd) interactions, which are essential ingredients for probing new physics beyond the standard model of particle interactions, differ substantially from the previous theoretical results. It is therefore necessary to perform an independent test of the validity of these results. In view of this, the normal coupled-cluster method has been extended to the relativistic regime [relativistic normal coupled-cluster (RNCC) method] to calculate the EDMs of atoms by simultaneously incorporating the electrostatic and P ,T -odd interactions in order to overcome the shortcomings of the ordinary RCC method. This new relativistic method has been applied to 199Hg, which currently has a lower EDM limit than that of any other system. The results of our RNCC and self-consistent RCC calculations of the EDM of this atom are found to be close. The discrepancies between these two results on the one hand and those of previous calculations on the other are elucidated. Furthermore, the electric dipole polarizability of this atom, which has computational similarities with the EDM, is evaluated and it is in very good agreement with its measured value.

Relativistic Normal Coupled-Cluster Theory for Accurate Determination of Electric Dipole Moments of Atoms: First Application to the ^{199}Hg Atom.

PubMed

Sahoo, B K; Das, B P

2018-05-18

Recent relativistic coupled-cluster (RCC) calculations of electric dipole moments (EDMs) of diamagnetic atoms due to parity and time-reversal violating (P,T-odd) interactions, which are essential ingredients for probing new physics beyond the standard model of particle interactions, differ substantially from the previous theoretical results. It is therefore necessary to perform an independent test of the validity of these results. In view of this, the normal coupled-cluster method has been extended to the relativistic regime [relativistic normal coupled-cluster (RNCC) method] to calculate the EDMs of atoms by simultaneously incorporating the electrostatic and P,T-odd interactions in order to overcome the shortcomings of the ordinary RCC method. This new relativistic method has been applied to ^{199}Hg, which currently has a lower EDM limit than that of any other system. The results of our RNCC and self-consistent RCC calculations of the EDM of this atom are found to be close. The discrepancies between these two results on the one hand and those of previous calculations on the other are elucidated. Furthermore, the electric dipole polarizability of this atom, which has computational similarities with the EDM, is evaluated and it is in very good agreement with its measured value.

Microscopic multiphonon approach to spectroscopy in the neutron-rich oxygen region

NASA Astrophysics Data System (ADS)

De Gregorio, G.; Knapp, F.; Lo Iudice, N.; Veselý, P.

2018-03-01

Background: A fairly rich amount of experimental spectroscopic data have disclosed intriguing properties of the nuclei in the region of neutron rich oxygen isotopes up to the neutron dripline. They, therefore, represent a unique laboratory for studying the evolution of nuclear structure away from the stability line. Purpose: We intend to give an exhaustive microscopic description of low and high energy spectra, dipole response, weak, and electromagnetic properties of the even 22O and the odd 23O and 23F. Method: An equation of motion phonon method generates an orthonormal basis of correlated n -phonon states (n =0 ,1 ,2 ,⋯ ) built of constituent Tamm-Dancoff phonons. This basis is adopted to solve the full eigenvalue equations in even nuclei and to construct an orthonormal particle-core basis for the eigenvalue problem in odd nuclei. No approximations are involved and the Pauli principle is taken into full account. The method is adopted to perform self-consistent, parameter free, calculations using an optimized chiral nucleon-nucleon interaction in a space encompassing up to two-phonon basis states. Results: The computed spectra in 22O and 23O and the dipole cross section in 22O are in overall agreement with the experimental data. The calculation describes poorly the spectrum of 23F. Conclusions: The two-phonon configurations play a crucial role in the description of spectra and transitions. The large discrepancies concerning the spectra of 23F are ultimately traced back to the large separation between the Hartree-Fock levels belonging to different major shells. We suggest that a more compact single particle spectrum is needed and can be generated by a new chiral potential which includes explicitly the contribution of the three-body forces.

QRAP: A numerical code for projected (Q)uasiparticle (RA)ndom (P)hase approximation

NASA Astrophysics Data System (ADS)

Samana, A. R.; Krmpotić, F.; Bertulani, C. A.

2010-06-01

A computer code for quasiparticle random phase approximation - QRPA and projected quasiparticle random phase approximation - PQRPA models of nuclear structure is explained in details. The residual interaction is approximated by a simple δ-force. An important application of the code consists in evaluating nuclear matrix elements involved in neutrino-nucleus reactions. As an example, cross sections for 56Fe and 12C are calculated and the code output is explained. The application to other nuclei and the description of other nuclear and weak decay processes are also discussed. Program summaryTitle of program: QRAP ( Quasiparticle RAndom Phase approximation) Computers: The code has been created on a PC, but also runs on UNIX or LINUX machines Operating systems: WINDOWS or UNIX Program language used: Fortran-77 Memory required to execute with typical data: 16 Mbytes of RAM memory and 2 MB of hard disk space No. of lines in distributed program, including test data, etc.: ˜ 8000 No. of bytes in distributed program, including test data, etc.: ˜ 256 kB Distribution format: tar.gz Nature of physical problem: The program calculates neutrino- and antineutrino-nucleus cross sections as a function of the incident neutrino energy, and muon capture rates, using the QRPA or PQRPA as nuclear structure models. Method of solution: The QRPA, or PQRPA, equations are solved in a self-consistent way for even-even nuclei. The nuclear matrix elements for the neutrino-nucleus interaction are treated as the beta inverse reaction of odd-odd nuclei as function of the transfer momentum. Typical running time: ≈ 5 min on a 3 GHz processor for Data set 1.

Descriptions of carbon isotopes within the energy density functional theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ismail, Atef; Cheong, Lee Yen; Yahya, Noorhana

2014-10-24

Within the energy density functional (EDF) theory, the structure properties of Carbon isotopes are systematically studied. The shell model calculations are done for both even-A and odd-A nuclei, to study the structure of rich-neutron Carbon isotopes. The EDF theory indicates the single-neutron halo structures in {sup 15}C, {sup 17}C and {sup 19}C, and the two-neutron halo structures in {sup 16}C and {sup 22}C nuclei. It is also found that close to the neutron drip-line, there exist amazing increase in the neutron radii and decrease on the binding energies BE, which are tightly related with the blocking effect and correspondingly themore » blocking effect plays a significant role in the shell model configurations.« less

Spectroscopic properties of nuclear skyrme energy density functionals.

PubMed

Tarpanov, D; Dobaczewski, J; Toivanen, J; Carlsson, B G

2014-12-19

We address the question of how to improve the agreement between theoretical nuclear single-particle energies (SPEs) and observations. Empirically, in doubly magic nuclei, the SPEs can be deduced from spectroscopic properties of odd nuclei that have one more or one less neutron or proton. Theoretically, bare SPEs, before being confronted with observations, must be corrected for the effects of the particle vibration coupling (PVC). In the present work, we determine the PVC corrections in a fully self-consistent way. Then, we adjust the SPEs, with PVC corrections included, to empirical data. In this way, the agreement with observations, on average, improves; nevertheless, large discrepancies still remain. We conclude that the main source of disagreement is still in the underlying mean fields, and not in including or neglecting the PVC corrections.

Rich interfacial chemistry and properties of carbon-doped hexagonal boron nitride nanosheets revealed by electronic structure calculations

NASA Astrophysics Data System (ADS)

Xie, Wei; Tamura, Takahiro; Yanase, Takashi; Nagahama, Taro; Shimada, Toshihiro

2018-04-01

The effect of C doping to hexagonal boron nitride (h-BN) to its electronic structure is examined by first principles calculations using the association from π-electron systems of organic molecules embedded in a two-dimensional insulator. In a monolayered carbon-doped structure, odd-number doping with carbon atoms confers metallic properties with different work functions. Various electronic interactions occur between two layers with odd-number carbon substitution. A direct sp3 covalent chemical bond is formed when C replaces adjacent B and N in different layers. A charge transfer complex between layers is found when C replaces B and N in the next-neighboring region, which results in narrower band gaps (e.g., 0.37 eV). Direct bonding between C and B atoms is found when two C atoms in different layers are at a certain distance.

Equilibrium geometries, electronic and magnetic properties of small AunNi- (n = 1-9) clusters

NASA Astrophysics Data System (ADS)

Tang, Cui-Ming; Chen, Xiao-Xu; Yang, Xiang-Dong

2014-05-01

Geometrical, electronic and magnetic properties of small AunNi- (n = 1-9) clusters have been investigated based on density functional theory (DFT) at PW91P86 level. An extensive structural search shows that the relative stable structures of AunNi- (n = 1-9) clusters adopt 2D structure for n = 1-5, 7 and 3D structure for n = 6, 8-9. And the substitution of a Ni atom for an Au atom in the Au-n+1 cluster obviously changes the structure of the host cluster. Moreover, an odd-even alternation phenomenon has been found for HOMO-LUMO energy gaps, indicating that the relative stable structures of the AunNi- clusters with odd-numbered gold atoms have a higher relative stability. Finally, the natural population analysis (NPA) and the vertical detachment energies (VDE) are studied, respectively. The theoretical values of VDE are reported for the first time to our best knowledge.

Saturated hydrocarbons in the background and contaminated soils of the cisurals

NASA Astrophysics Data System (ADS)

Gabov, D. N.; Beznosikov, V. A.; Kondratenok, B. M.; Gruzdev, I. V.

2010-10-01

A homologous series of n-alkanes (C20-C35) was identified in peaty-podzolic-gleyic soils. Structures with odd numbers of carbon atoms (C25-C35) were predominant in the soil organic matter. It was found that the major amount of both odd and even n-alkanes was accumulated in the peaty litter. In the mineral horizons, the mass fraction of the odd n-alkanes abruptly decreased to become comparable to that of the even n-alkanes in the soil-forming rock.

Observation of new neutron-rich Mn, Fe, Co, Ni, and Cu isotopes in the vicinity of 78Ni

NASA Astrophysics Data System (ADS)

Sumikama, T.; Nishimura, S.; Baba, H.; Browne, F.; Doornenbal, P.; Fukuda, N.; Franchoo, S.; Gey, G.; Inabe, N.; Isobe, T.; John, P. R.; Jung, H. S.; Kameda, D.; Kubo, T.; Li, Z.; Lorusso, G.; Matea, I.; Matsui, K.; Morfouace, P.; Mengoni, D.; Napoli, D. R.; Niikura, M.; Nishibata, H.; Odahara, A.; Sahin, E.; Sakurai, H.; Söderström, P.-A.; Stefan, G. I.; Suzuki, D.; Suzuki, H.; Takeda, H.; Taniuchi, R.; Taprogge, J.; Vajta, Zs.; Watanabe, H.; Werner, V.; Wu, J.; Xu, Z. Y.; Yagi, A.; Yoshinaga, K.

2017-05-01

Neutron-rich nuclei in the vicinity of 78Ni were produced using a 238U beam at the RIKEN Radioactive Isotope Beam Factory. The particle-identification plot for the in-flight fission fragments highlights the first observation of eight new isotopes: 73Mn, 76Fe, Co,7877, 80,81,82Ni, and 83Cu. Although the β -decay half-lives of 77Co and 80Ni were recently reported by Xu et al. [Phys. Rev. Lett. 113, 032505 (2014)], 10.1103/PhysRevLett.113.032505 using data from the same experiment, the current work provides the first direct, quantitative evidence for the existence of these isotopes. The experimental production cross sections are reproduced in a satisfactory manner by theoretical predictions. An odd-even staggering of the cross sections was observed, and the effect appears to become more pronounced for the most exotic nuclei that were investigated. The staggering effect was interpreted as an increase of the neutron-evaporation probability for odd-N isotopes, owing to the decrease of the neutron-separation energy, Sn. The predicted cross section for 80Ni is significantly overestimated, which may be related to a weak binding of the neutron pair above the N =50 shell closure.

Penning Trap Experiments with the Most Exotic Nuclei on Earth: Precision Mass Measurements of Halo Nuclei

NASA Astrophysics Data System (ADS)

Brodeur, M.; Brunner, T.; Ettenauer, S.; Lapierre, A.; Ringle, R.; Delheij, P.; Dilling, J.

2009-05-01

Exotic nuclei are characterized with an extremely unbalanced protons-neutrons ratio (p/n) where for instance, the halo isotopes of He and Li have up to 3X more n than p (compared to p/n = 1 in ^12C). The properties of these exotic halo nuclei have long been recognized as the most stringent tests of our understanding of the strong force. ^11Li belongs to a special category of halos called Borromean, bound as a three-body family, while the two-body siblings, ^10Li and 2 n, are unbound as separate entities. Last year, a first mass measurement of the radioisotope ^11Li using a Penning trap spectrometer was carried out at the TITAN (Triumf's Ion Trap for Atomic and Nuclear science) facility at TRIUMF-ISAC. Penning traps are proven to be the most precise device to make mass measurements, yet until now they were unable to reach these nuclei. At TRIUMF we managed to measure the mass of ^11Li to an unprecedented precision of dm/m = 60 ppb, which is remarkable since it has a half-life of only 8.8 ms which it the shortest-lived nuclide to be measured with this technique. Furthermore, new and improved masses for the 2 and 4 n halo ^6,8He, as well has the 1 n halo ^11Be have been performed. An overview of the TITAN mass measurement program and its impact in understanding the most exotic nuclei will be given.

The structure of nuclei far from stability. [Dept. of Physics and Astronomy, Louisiana State Univ. , Baton Rouge, Louisiana

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zganjar, E.F.

1993-01-01

Studies on nuclei near Z=82 contributed to the establishment of a new region of nuclear deformation and a new class of nuclear structure at closed shells. A important aspect of this work is the establishment of the connection between low-lying 0[sup +] states in even[endash]even nuclei and the occurrence of shape coexistence in the odd-mass neighbors (E0 transitions in [sup 185]Pt, shape coexistence in [sup 184]Pt and [sup 187]Au). A new type of picosecond lifetime measurement system capable of measuring the lifetime of states that decay only by internal conversion was developed and applied to the [sup 186,188]Tl decay tomore » determine the lifetime of the 0[sub 2][sup +] and 2[sub 2][sup +] deformed states in [sup 186,188]Hg. A search for the population of superdeformed states in [sup 192]Hg by the radioactive decay of [sup 192]Tl was accomplished by using a prototype internal pair formation spectrometer.« less

PET - A proton/electron telescope for studies of magnetospheric, solar, and galactic particles

NASA Technical Reports Server (NTRS)

Cook, Walter R.; Cummings, Alan C.; Cummings, Jay R.; Garrard, Thomas L.; Kecman, Branislav; Mewaldt, Richard A.; Selesnick, Richard S.; Stone, Edward C.; Baker, Daniel N.; Von Rosenvinge, Tycho T.

1993-01-01

The Proton/Electron Telescope (PET) on SAMPEX is designed to provide measurements of energetic electrons and light nuclei from solar, galactic, and magnetospheric sources. PET is an all solid-state system that will measure the differential energy spectra of electrons from about 1 to about 30 MeV and H and He nuclei from about 20 to about 300 MeV/nuc, with isotope resolution of H and He extending from about 20 to about 80 MeV/nuc. As SAMPEX scans all local times and geomagnetic cutoffs over the course of its near-polar orbit, PET will characterize precipitating relativistic electron events during periods of declining solar activity, and it will examine whether the production rate of odd nitrogen and hydrogen molecules in the middle atmosphere by precipitating electrons is sufficient to affect O3 depletion. In addition, PET will complement studies of the elemental and isotopic composition of energetic heavy (Z greater than 2) nuclei on SAMPEX by providing measurements of H, He, and electrons. Finally, PET has limited capability to identify energetic positrons from potential natural and man-made sources.

Isomer spectroscopy of neutron-rich $$^{165,167}$$Tb

DOE PAGES

Gurgi, L. A.; Regan, P. H.; Soderstrom, P. -A.; ...

2017-01-01

We present information on the excited states in the prolate-deformed, neutron-rich nuclei 165,167Tb 100,102. The nuclei of interest were synthesised following in-flight fission of a 345 MeV per nucleon 238U primary beam on a 2 mm 9Be target at the Radioactive Ion-Beam Factory (RIBF), RIKEN, Japan. The exotic nuclei were separated and identified event-by-event using the BigRIPS separator, with discrete energy gamma-ray decays from isomeric states with half-lives in the μs regime measured using the EURICA gamma-ray spectrometer. Metastable-state decays are identified in 165Tb and 167Tb and interpreted as arising from hindered E1 decay from the 72 –[523] single quasi-protonmore » Nilsson configuration to rotational states built on the 32 –[411] single quasi-proton ground state. Lastly, these data correspond to the first spectroscopic information in the heaviest, odd-A terbium isotopes reported to date and provide information on proton Nilsson configurations which reside close to the Fermi surface as the 170Dy doubly-midshell nucleus is approached.« less

Systematic study of α preformation probability of nuclear isomeric and ground states

NASA Astrophysics Data System (ADS)

Sun, Xiao-Dong; Wu, Xi-Jun; Zheng, Bo; Xiang, Dong; Guo, Ping; Li, Xiao-Hua

2017-01-01

In this paper, based on the two-potential approach combining with the isospin dependent nuclear potential, we systematically compare the α preformation probabilities of odd-A nuclei between nuclear isomeric states and ground states. The results indicate that during the process of α particle preforming, the low lying nuclear isomeric states are similar to ground states. Meanwhile, in the framework of single nucleon energy level structure, we find that for nuclei with nucleon number below the magic numbers, the α preformation probabilities of high-spin states seem to be larger than low ones. For nuclei with nucleon number above the magic numbers, the α preformation probabilities of isomeric states are larger than those of ground states. Supported by National Natural Science Foundation of China (11205083), Construct Program of Key Discipline in Hunan Province, Research Foundation of Education Bureau of Hunan Province, China (15A159), Natural Science Foundation of Hunan Province, China (2015JJ3103, 2015JJ2123), Innovation Group of Nuclear and Particle Physics in USC, Hunan Provincial Innovation Foundation for Postgraduate (CX2015B398)

Nuclear magnetic resonance studies of quadrupolar nuclei and dipolar field effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Urban, Jeffry Todd

Experimental and theoretical research conducted in two areas in the field of nuclear magnetic resonance (NMR) spectroscopy is presented: (1) studies of the coherent quantum-mechanical control of the angular momentum dynamics of quadrupolar (spin I > 1/2) nuclei and its application to the determination of molecular structure; and (2) applications of the long-range nuclear dipolar field to novel NMR detection methodologies.The dissertation is organized into six chapters. The first two chapters and associated appendices are intended to be pedagogical and include an introduction to the quantum mechanical theory of pulsed NMR spectroscopy and the time dependent theory of quantum mechanics.more » The third chapter describes investigations of the solid-state multiple-quantum magic angle spinning (MQMAS) NMR experiment applied to I = 5/2 quadrupolar nuclei. This work reports the use of rotary resonance-matched radiofrequency irradiation for sensitivity enhancement of the I = 5/2 MQMAS experiment. These experiments exhibited certain selective line narrowing effects which were investigated theoretically.The fourth chapter extends the discussion of multiple quantum spectroscopy of quadrupolar nuclei to a mostly theoretical study of the feasibility of enhancing the resolution of nitrogen-14 NMR of large biomolecules in solution via double-quantum spectroscopy. The fifth chapter continues to extend the principles of multiple quantum NMR spectroscopy of quadrupolar nuclei to make analogies between experiments in NMR/nuclear quadrupolar resonance (NQR) and experiments in atomic/molecular optics (AMO). These analogies are made through the Hamiltonian and density operator formalism of angular momentum dynamics in the presence of electric and magnetic fields.The sixth chapter investigates the use of the macroscopic nuclear dipolar field to encode the NMR spectrum of an analyte nucleus indirectly in the magnetization of a sensor nucleus. This technique could potentially serve as an encoding module for the recently developed NMR remote detection experiment. The feasibility of using hyperpolarized xenon-129 gas as a sensor is discussed. This work also reports the use of an optical atomic magnetometer to detect the nuclear magnetization of Xe-129 gas, which has potential applicability as a detection module for NMR remote detection experiments.« less

Nuclear Structure of 186Re

DTIC Science & Technology

2016-12-24

D population-depopulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 AME Atomic Mass Evaluation...this mass region are important for validating models of nuclear structure and reactions. The ENSDF feeds a specific data library relevant to nuclear...spherically asymmetric. Spherical asymmetry is common for nuclei between shell closures, such as those in the mid-shell 150  A  190 mass range of interest

What Is a Chemical Element?

ERIC Educational Resources Information Center

ten Hoor, Marten J.

2017-01-01

Contrary to current IUPAC recommendations, the chemical element X should be defined as the nucleus of the X atom. Consequently, different isotopes with their different nuclei belong to different elements, each one with its own physical and chemical properties. This view leads to the conclusion that we no longer have a periodic table of the…

A Geant4-based Simulation to Evaluate the Feasibility of Using Nuclear Resonance Fluorescence (NRF) in Determining Atomic Compositions of Body Tissue in Cancer Diagnostics and Irradiation

NASA Astrophysics Data System (ADS)

Gilbo, Yekaterina; Wijesooriya, Krishni; Liyanage, Nilanga

2017-01-01

Customarily applied in homeland security for identifying concealed explosives and chemical weapons, NRF (Nuclear Resonance Fluorescence) may have high potential in determining atomic compositions of body tissue. High energy photons incident on a target excite the target nuclei causing characteristic re-emission of resonance photons. As the nuclei of each isotope have well-defined excitation energies, NRF uniquely indicates the isotopic content of the target. NRF radiation corresponding to nuclear isotopes present in the human body is emitted during radiotherapy based on Bremsstrahlung photons generated in a linear electron accelerator. We have developed a Geant4 simulation in order to help assess NRF capabilities in detecting, mapping, and characterizing tumors. We have imported a digital phantom into the simulation using anatomical data linked to known chemical compositions of various tissues. Work is ongoing to implement the University of Virginia's cancer center treatment setup and patient geometry, and to collect and analyze the simulation's physics quantities to evaluate the potential of NRF for medical imaging applications. Preliminary results will be presented.

Towards Single Biomolecule Imaging via Optical Nanoscale Magnetic Resonance Imaging.

PubMed

Boretti, Alberto; Rosa, Lorenzo; Castelletto, Stefania

2015-09-09

Nuclear magnetic resonance (NMR) spectroscopy is a physical marvel in which electromagnetic radiation is charged and discharged by nuclei in a magnetic field. In conventional NMR, the specific nuclei resonance frequency depends on the strength of the magnetic field and the magnetic properties of the isotope of the atoms. NMR is routinely utilized in clinical tests by converting nuclear spectroscopy in magnetic resonance imaging (MRI) and providing 3D, noninvasive biological imaging. While this technique has revolutionized biomedical science, measuring the magnetic resonance spectrum of single biomolecules is still an intangible aspiration, due to MRI resolution being limited to tens of micrometers. MRI and NMR have, however, recently greatly advanced, with many breakthroughs in nano-NMR and nano-MRI spurred by using spin sensors based on an atomic impurities in diamond. These techniques rely on magnetic dipole-dipole interactions rather than inductive detection. Here, novel nano-MRI methods based on nitrogen vacancy centers in diamond are highlighted, that provide a solution to the imaging of single biomolecules with nanoscale resolution in-vivo and in ambient conditions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Metal-nonmetal oscillations in doped blue phosphorene: a first-principles study

NASA Astrophysics Data System (ADS)

Li, Hui; Zhang, Liwei; Cai, Xiaolin; Li, Xiaohua; Wang, Baoji; Yu, Weiyang; Zhao, Ruiqi

2018-05-01

Based on density functional theory (DFT), we have systematically investigated the geometry structure and electronic properties of group IIIA, IVA, VA, and VIA atoms doped blue phosphorene, such as B‑, C‑, N‑, O‑, Al‑, Si- and S-doped blue phosphorene systems. We find that the electronic properties of blue phosphorene are drastically modified by the number of valence electrons in dopant atoms. An intriguing general rule of metal-nonmetal oscillations have been obtained that the dopant atoms from even group, such as IVA and VIA, lead to metal properties, while dopant atoms from odd group, such as IIIA and VA, give rise to semiconductor properties, which is different from traditional n or p doping effect in bulk case. This even–odd oscillating behavior is attributed to the peculiar bonding characteristics of blue phosphorene and the strong hybridization of sp orbitals between dopants and blue phosphorene. Then the underlying mechanism has been investigated with the electronic filling analysis. These results pave an intriguing way to tune the transport properties of electronic and photoelectronic devices based on blue phosphorene.

Empirical moments of inertia of axially asymmetric nuclei

DOE PAGES

Allmond, J. M.; Wood, J. L.

2017-02-06

We extracted empirical moments of inertia, J1, J2, J3, of atomic nuclei with E(4more » $$+\\atop{1}$$)/E(2$$+\\atop{1}$$ ) > 2.7 from experimental 2$$+\\atop{g,y}$$, energies and electric quadrupole matrix elements, determined from multi- step Coulomb excitation data, and the results are compared to expectations based on rigid and irro- tational inertial flow. Only by having the signs of the E2 matrix elements, i.e., <2$$+\\atop{g}$$ ||M (E2)||2$$+\\atop{g}$$> and <0$$+\\atop{g}$$ ||M (E2)||2$$+\\atop{g}$$> < 2$$+\\atop{g}$$ ||M (E2)||2$$+\\atop{γ}$$> <2$$+\\atop{γ}$$ ||M (E2)||0$$+\\atop{g}$$> , can a unique solution to all three components of the inertia tensor of an asymmetric top be obtained. And while the absolute moments of inertia fall between the rigid and irrotational values as expected, the relative moments of inertia appear to be qualitatively consistent with the β 2 sin 2(γ ) dependence of the Bohr Hamiltonian which originates from a SO(5) in- variance. A better understanding of inertial flow is central to improving collective models, particularly hydrodynamic-based collective models. The results suggest that a better description of collective dynamics and inertial flow for atomic nuclei is needed. The inclusion of vorticity degrees of freedom may provide a path forward. This is our first report of empirical moments of inertia for all three axes and the results should challenge both collective and microscopic descriptions of inertial flow.« less

Inelastic proton scattering and particle-vibration coupling in /sup 115/Sn, /sup 117/Sn, and /sup 119/Sn

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fleming, D.G.; Becchetti, F.D.; Flynn, E.R.

Inelastic proton scattering on the stable odd-A tin isotopes /sup 115/Sn, /sup 117/Sn, and /sup 119/Sn has been carried out at 18 MeV on isotope separated targets. Angular distributions were not obtained but, nevertheless, the individual spectra reveal a large number of strongly populated states in the energy region of the known octupole strength of the even-A nuclei, permitting several new (tentative) 5/2/sup -/,7/2/sup -/ spin assignments. General comparisons are made of the observed relative strengths with those obtained from other reactions populating the same final states, revealing a complex nuclear structure in the odd-A tins which is not understoodmore » theoretically.« less

Understanding glass-forming ability through sluggish crystallization of atomically thin metallic glassy films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Y. T.; Cao, C. R.; Huang, K. Q.

2014-08-04

The glass-forming ability (GFA) of an alloy, closely related to its ability to resist crystallization, is a crucial issue in condensed matter physics. So far, the studies on GFA are mostly statistical and empirical guides. Benefiting from the ultrahigh thermal stability of ultrathin metallic glassy film and high resolution spherical aberration-corrected transmission electron microscope, the crystallization of atomically thin ZrCu and its microalloyed ZrCuAl glasses with markedly different GFA was investigated at the atomic scale. We find the Zr diffusivity estimated from the density of nuclei is dramatically decreased by adding of Al, which is the major reason for themore » much better GFA of the ZrCuAl metallic glass.« less

Alpha Decay Potential Barriers and Half-Lives and Analytical Formula Predictions for Superheavy Nuclei

NASA Astrophysics Data System (ADS)

Royer, Guy; Zhang, Hongfei

The α decay potential barriers are determined in the cluster-like shape path within a generalized liquid drop model including the proximity effects between the α particle and the daughter nucleus and adjusted to reproduce the experimental Qα. The α emission half-lives are determined within the WKB penetration probability. Calculations using previously proposed formulae depending only on the mass and charge of the alpha emitter and Qα are also compared with new experimental alpha-decay half-lives. The agreement allows to provide predictions for the α decay half-lives of other still unknown superheavy nuclei using the Qα determined from the 2003 atomic mass evaluation of Audi, Wapstra and Thibault.

The QSE-Reduced Nuclear Reaction Network for Silicon Burning

NASA Astrophysics Data System (ADS)

Hix, W. Raphael; Parete-Koon, Suzanne T.; Freiburghaus, Christian; Thielemann, Friedrich-Karl

2007-09-01

Iron and neighboring nuclei are formed in massive stars shortly before core collapse and during their supernova outbursts, as well as during thermonuclear supernovae. Complete and incomplete silicon burning are responsible for the production of a wide range of nuclei with atomic mass numbers from 28 to 64. Because of the large number of nuclei involved, accurate modeling of silicon burning is computationally expensive. However, examination of the physics of silicon burning has revealed that the nuclear evolution is dominated by large groups of nuclei in mutual equilibrium. We present a new hybrid equilibrium-network scheme which takes advantage of this quasi-equilibrium in order to reduce the number of independent variables calculated. This allows accurate prediction of the nuclear abundance evolution, deleptonization, and energy generation at a greatly reduced computational cost when compared to a conventional nuclear reaction network. During silicon burning, the resultant QSE-reduced network is approximately an order of magnitude faster than the full network it replaces and requires the tracking of less than a third as many abundance variables, without significant loss of accuracy. These reductions in computational cost and the number of species evolved make QSE-reduced networks well suited for inclusion within hydrodynamic simulations, particularly in multidimensional applications.

Empirical p-n interactions, the synchronized filling of Nilsson orbitals, and emergent collectivity

NASA Astrophysics Data System (ADS)

Cakirli, R. B.

2014-09-01

The onset of collectivity and deformation, changes to the single particle energies and magic numbers and so on are strongly influenced by, for example, proton (p) and neutron (n) interactions inside atomic nuclei. Experimentally, using binding energies (or masses), one can extract an average p-n interaction between the last two protons and the last two neutrons, called δVpn. We have studied δVpn values using calculations of spatial overlaps between p and n Nilsson orbitals, considering different deformations, for the Z= 50-82, N= 82-126 shells, and comparison of these theoretical results with experimental δVpn values. Our results show that enhanced valence p-n interactions are closely correlated with the development of collectivity, shape changes, and the saturation of deformation in nuclei. We note that the difference of the Nilsson quantum numbers of the last filled Nilsson p and n orbitals, has a special relation, 0[110], in which they differ by only a single quantum in the z-direction, for those nuclei where δVpn is largest for each Z in medium mass and heavy nuclei. The synchronised filling of such orbital pairs correlates with the emergence of collectivity.

Emergent properties of nuclei from ab initio coupled-cluster calculations

NASA Astrophysics Data System (ADS)

Hagen, G.; Hjorth-Jensen, M.; Jansen, G. R.; Papenbrock, T.

2016-06-01

Emergent properties such as nuclear saturation and deformation, and the effects on shell structure due to the proximity of the scattering continuum and particle decay channels are fascinating phenomena in atomic nuclei. In recent years, ab initio approaches to nuclei have taken the first steps towards tackling the computational challenge of describing these phenomena from Hamiltonians with microscopic degrees of freedom. This endeavor is now possible due to ideas from effective field theories, novel optimization strategies for nuclear interactions, ab initio methods exhibiting a soft scaling with mass number, and ever-increasing computational power. This paper reviews some of the recent accomplishments. We also present new results. The recently optimized chiral interaction NNLO{}{{sat}} is shown to provide an accurate description of both charge radii and binding energies in selected light- and medium-mass nuclei up to 56Ni. We derive an efficient scheme for including continuum effects in coupled-cluster computations of nuclei based on chiral nucleon-nucleon and three-nucleon forces, and present new results for unbound states in the neutron-rich isotopes of oxygen and calcium. The coupling to the continuum impacts the energies of the {J}π =1/{2}-,3/{2}-,7/{2}-,3/{2}+ states in {}{17,23,25}O, and—contrary to naive shell-model expectations—the level ordering of the {J}π =3/{2}+,5/{2}+,9/{2}+ states in {}{53,55,61}Ca. ).

Systematic features in the structure of doubly odd nuclei around A~=80 mass region: Band structure in 76Rb

NASA Astrophysics Data System (ADS)

García Bermúdez, G.; Baktash, C.; Lister, C. J.; Cardona, M. A.

1988-08-01

Multiple-particle γ-ray coincidence techniques have been used to establish the high spin structure of 76Rb. Two ΔI=1 bands were found built on the Iπ=1- ground state and on the Iπ=(4+) isomeric state at 316.8 keV energy. Systematic of positive parity bands seen in the Br-Kr-Rb isotones with N=39 and 41 is discussed.

Estimation of the alpha decay of Platinum isotopes using different versions of theoretical formula

NASA Astrophysics Data System (ADS)

Hosseini, S. S.; Hassanabadi, H.; Sobhani, H.

The alpha decay half-lives of even-even and even-odd Platinum (Pt) nuclei have been studied within the Coulomb and proximity potential model (CPPM). The present study is restricted to even-even nuclei with A = 166-198. The results are compared with other calculations such as the Semi-empirical formula (SemFIS) from Poenaru et al. based on fission theory of alpha decay, the Viola-Seaborg (VS), Royer (R) and Brown formulae. Also, the alpha decay half-lives have been calculated using the Scaling law of Brown (SLB), the Universal Decay Law (UDL) of Qi et al., the Scaling Law of Horoi et al. (SLH), and Akrawy-Dorin formula (ADF) of Akrawy and Poenaru, which are the Royer modified formula for alpha decay half-live by adding asymmetry term.

Limits on Lorentz Invariance Violation from Coulomb Interactions in Nuclei and Atoms.

PubMed

Flambaum, V V; Romalis, M V

2017-04-07

Anisotropy in the speed of light that has been constrained by Michelson-Morley-type experiments also generates anisotropy in the Coulomb interactions. This anisotropy can manifest itself as an energy anisotropy in nuclear and atomic experiments. Here the experimental limits on Lorentz violation in _{10}^{21}Ne are used to improve the limits on Lorentz symmetry violations in the photon sector, namely, the anisotropy of the speed of light and the Coulomb interactions, by 7 orders of magnitude in comparison with previous experiments: the speed of light is isotropic to a part in 10^{28}.

The nuclear contacts and short range correlations in nuclei

NASA Astrophysics Data System (ADS)

Weiss, R.; Cruz-Torres, R.; Barnea, N.; Piasetzky, E.; Hen, O.

2018-05-01

Atomic nuclei are complex strongly interacting systems and their exact theoretical description is a long-standing challenge. An approximate description of nuclei can be achieved by separating its short and long range structure. This separation of scales stands at the heart of the nuclear shell model and effective field theories that describe the long-range structure of the nucleus using a mean-field approximation. We present here an effective description of the complementary short-range structure using contact terms and stylized two-body asymptotic wave functions. The possibility to extract the nuclear contacts from experimental data is presented. Regions in the two-body momentum distribution dominated by high-momentum, close-proximity, nucleon pairs are identified and compared to experimental data. The amount of short-range correlated (SRC) nucleon pairs is determined and compared to measurements. Non-combinatorial isospin symmetry for SRC pairs is identified. The obtained one-body momentum distributions indicate dominance of SRC pairs above the nuclear Fermi-momentum.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Winter, Frank; Detmold, William; Gambhir, Arjun S.

The role of gluons in the structure of the nucleon and light nuclei is investigated using lattice quantum chromodynamics (QCD) calculations. The first moment of the unpolarised gluon distribution is studied in nuclei up to atomic numbermore » $A=3$ at quark masses corresponding to pion masses of $$m_\\pi\\sim 450$$ and $806$ MeV. Nuclear modification of this quantity defines a gluonic analogue of the EMC effect and is constrained to be less than $$\\sim 10$$% in these nuclei. This is consistent with expectations from phenomenological quark distributions and the momentum sum rule. In the deuteron, the combination of gluon distributions corresponding to the $$b_1$$ structure function is found to have a small first moment compared with the corresponding momentum fraction. The first moment of the gluon transversity structure function is also investigated in the spin-1 deuteron, where a non-zero signal is observed at $$m_\\pi \\sim 806$$ MeV. In conclusion, this is the first indication of gluon contributions to nuclear structure that can not be associated with an individual nucleon.« less

The Z2/A dependence in heavy-ion fusion for the reactions of chlorine on thulium, lutetium, tantalum and tungsten. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

DiRienzo, A.C.

1980-06-01

Evaporation residues produced in the reactions 35Cl+169Tm and 37Cl+169Tm, 175Lu, 181Ta and 186W were observed at zero degree utilizing the Mass Inst of Tech.- Brookhaven Nat'l Lab Recoil Mass Spectrometer. The recoiling nuclei were separated from the beam and refocused onto a surface barrier detector by a combination of electrostatic and magnetic fields and magnetic quadrupole lenses. The residual nuclei are alpha radioactive and can thus be identified by a characteristic alpha line observed after the arrival pulse of the evaporation residue. The recoiling nuclei also pass through a gas ionization chamber whereas the decay alpha do not. A separatemore » anti-coincidence spectrum therefore displayed the alphas background free. Trends of evaporation residue cross section were charted versus Z sq (proton no.)/ A(atomic no.) and compared to statistical evaporation codes.« less

Coulomb Excitation of Exotic Nuclei

NASA Astrophysics Data System (ADS)

Macchiavelli, Augusto O.

2017-09-01

The structure of nuclei far from the stability line is a central theme of research in nuclear physics. Key to this program has been the worldwide development of radioactive beam facilities and novel detector systems, which provide the tools needed to produce and study these exotic nuclei. Coulomb Excitation provides a unique probe to characterize the interplay of collective and single-particle degrees of freedom of the atomic nucleus. In particular, the combination of state-of-the-art charged particle detectors and gamma-ray spectroscopy plays a vital and ubiquitous role in these studies. As an introduction to this Mini-Symposium, I will present a short overview of this powerful technique and selected examples of recent experiments. Future opportunities with a 4 π gamma-ray tracking array like GRETA will be discussed. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Contract No. DE-AC02-05CH11231 (LBNL).

Electron capture by U(91+) and U(92+) and ionization of U(90+) and U(91+)

NASA Technical Reports Server (NTRS)

Gould, H.; Greiner, D.; Lindstrom, P.; Symons, T. J. M.; Crawford, H.

1984-01-01

U(92+)/U(91+) and U(91+)/U(90+) electron-capture and ionization cross sections and equilibrium charge-state distributions are measured experimentally in mylar, Cu and Ta of varying thickness. Relativistic U(68+) ions at 437 or 962 MeV/nucleon are produced by a heavy-ion linear accelerator and synchrotron in tandem and passed through the target material into a magnetic specrometer and position-sensitive proportional counter for evaluation of charge states. The results are presented graphically and discussed. At 962 MeV/nucleon, beams containing 85 percent bare U(92+) nuclei are obtained using 150-mg/sq cm Cu or 85-mg/sq cm Ta; at 437 MeV/nucleon, 50 percent bare U(92+) nuclei are obtained with 90-mg/sq cm Cu. The techniques decribed can be applied to produce beams of bare U nuclei for acceleration to ultrarelativistic speeds or beams of few-electron U for atomic-physics experiments on quantum electrodynamics.

SuperTIGER: On the Cosmic Ray Charge Frontier

NASA Astrophysics Data System (ADS)

Brandt, Theresa J.

2017-08-01

The Super Trans-Iron Galactic Element Recorder (SuperTIGER) was designed to measure significant statistics particularly for cosmic rays (CRs) with charge > 30. These heaviest nuclei are some 10^3-10^5 times rarer than the lighter elements. With the longest science flight to date on a Long Duration Balloon in 2012-13, SuperTIGER has collected >1200 of these rare nuclei and millions of lighter CR events. After the instrument spent two winters in Antarctica, we recovered it and are completing preparations for a second flight. We present results from the first flight, including the highest statistical precision measurements of CR charges from 30-40 to date. We anticipate even greater improvements with our second flight, this coming austral summer, 2017-18 from McMurdo, Antarctica. The results show enhanced numbers of elements formed in massive stars relative to solar system values, and thus give insight into the origin of Galactic CRs, likely in OB associations, and into the atomic processes which accelerate nuclei.

Light Flashes Observed by Astronauts on Apollo 11 through Apollo 17.

PubMed

Pinsky, L S; Osborne, W Z; Bailey, J V; Benson, R E; Thompson, L F

1974-03-08

The crew members on the last seven Apollo flights observed light flashes that are tentatively attributed to cosmic ray nuclei (atomic number >/= 6) penetrating the head and eyes of the observers. Analyses of the event rates for all missions has revealed an anomalously low rate for transearth coast observations with respect to translunar coast observations.

Maria Goeppert Mayer, the Nuclear Shell Structure, and Magic Numbers

Science.gov Websites

dropdown arrow Site Map A-Z Index Menu Synopsis Maria Goeppert-Mayer, the Nuclear Shell Model, and Magic explanation of how neutrons and protons within atomic nuclei are structured. Called the "nuclear shell American husband, chemical physicist Joseph Mayer. At Argonne, Goeppert-Mayer learned most of her nuclear

Study of breakup and transfer of weakly bound nucleus 6Li to explore the low energy reaction dynamics

NASA Astrophysics Data System (ADS)

Zhang, G. L.; Zhang, G. X.; Hu, S. P.; Zhang, H. Q.; Gomes, P. R. S.; Lubian, J.; Guo, C. L.; Wu, X. G.; Yang, J. C.; Zheng, Y.; Li, C. B.; He, C. Y.; Zhong, J.; Li, G. S.; Yao, Y. J.; Guo, M. F.; Sun, H. B.; Valiente-Dobòn, J. J.; Goasduff, A.; Siciliano, M.; Galtarosa, F.; Francesco, R.; Testov, D.; Mengoni, D.; Bazzacco, D.; John, P. R.; Qu, W. W.; Wang, F.; Zheng, L.; Yu, L.; Chen, Q. M.; Luo, P. W.; Li, H. W.; Wu, Y. H.; Zhou, W. K.; Zhu, B. J.; Li, E. T.; Hao, X.

2017-11-01

Investigation of the breakup and transfer effect of weakly bound nuclei on the fusion process has been an interesting research topic in the past several years. However, owing to the low intensities of the presently available radioactive ion beam (RIB), it is difficult to clearly explore the reaction mechanisms of nuclear systems with unstable nuclei. In comparison with RIB, the beam intensities of stable weakly bound nuclei such as 6,7Li and 9Be, which have significant breakup probability, are orders of magnitude higher. Precise fusion measurements have already been performed with those stable weakly bound nuclei, and the effect of breakup of those nuclei on the fusion process has been extensively studied. Those nuclei indicated large production cross sections for particles other than the α + x breakup. The particles are originated from non-capture breakup (NCBU), incomplete fusion (ICF) and transfer processes. However, the conclusion of reaction dynamics was not clear and has the contradiction. In our previous experiments we have performed 6Li+96Zr and 154Sm at HI-13 Tandem accelerator of China Institute of Atomic Energy (CIAE) by using HPGe array. It is shown that there is a small complete fusion (CF) suppression on medium-mass target nucleus 96Zr different from about 35% suppression on heavier target nucleus 154Sm at near-barrier energies. It seems that the CF suppression factor depends on the charge of target nuclei. We also observed one neutron transfer process. However, the experimental data are scarce for medium-mass target nuclei. In order to have a proper understanding of the influence of breakup and transfer of weakly bound projectiles on the fusion process, we performed the 6Li+89Y experiment with incident energies of 22 MeV and 34 MeV on Galileo array in cooperation with Si-ball EUCLIDES at Legnaro National Laboratory (LNL) in Italy. Using particle-particle and particle-γ coincidences, the different reaction mechanisms can be clearly explored.

Sub-barrier quasifission in heavy element formation reactions with deformed actinide target nuclei

NASA Astrophysics Data System (ADS)

Hinde, D. J.; Jeung, D. Y.; Prasad, E.; Wakhle, A.; Dasgupta, M.; Evers, M.; Luong, D. H.; du Rietz, R.; Simenel, C.; Simpson, E. C.; Williams, E.

2018-02-01

Background: The formation of superheavy elements (SHEs) by fusion of two massive nuclei is severely inhibited by the competing quasifission process. Low excitation energies favor SHE survival against fusion-fission competition. In "cold" fusion with spherical target nuclei near 208Pb, SHE yields are largest at beam energies significantly below the average capture barrier. In "hot" fusion with statically deformed actinide nuclei, this is not the case. Here the elongated deformation-aligned configurations in sub-barrier capture reactions inhibits fusion (formation of a compact compound nucleus), instead favoring rapid reseparation through quasifission. Purpose: To determine the probabilities of fast and slow quasifission in reactions with prolate statically deformed actinide nuclei, through measurement and quantitative analysis of the dependence of quasifission characteristics at beam energies spanning the average capture barrier energy. Methods: The Australian National University Heavy Ion Accelerator Facility and CUBE fission spectrometer have been used to measure fission and quasifission mass and angle distributions for reactions with projectiles from C to S, bombarding Th and U target nuclei. Results: Mass-asymmetric quasifission occurring on a fast time scale, associated with collisions with the tips of the prolate actinide nuclei, shows a rapid increase in probability with increasing projectile charge, the transition being centered around projectile atomic number ZP=14 . For mass-symmetric fission events, deviations of angular anisotropies from expectations for fusion fission, indicating a component of slower quasifission, suggest a similar transition, but centered around ZP˜8 . Conclusions: Collisions with the tips of statically deformed prolate actinide nuclei show evidence for two distinct quasifission processes of different time scales. Their probabilities both increase rapidly with the projectile charge. The probability of fusion can be severely suppressed by these two quasifission processes, since the sub-barrier heavy element yield is likely to be determined by the product of the probabilities of surviving each quasifission process.

Shielding materials for highly penetrating space radiations

NASA Technical Reports Server (NTRS)

Kiefer, Richard L.; Orwoll, Robert A.

1995-01-01

Interplanetary travel involves the transfer from an Earth orbit to a solar orbit. Once outside the Earth's magnetosphere, the major sources of particulate radiation are solar cosmic rays (SCR's) and galactic cosmic rays (GCR's). Intense fluxes of SCR's come from solar flares and consist primarily of protons with energies up to 1 GeV. The GCR consists of a low flux of nuclei with energies up to 10(exp 10) GeV. About 70 percent of the GCR are protons, but a small amount (0.6 percent) are nuclei with atomic numbers greater than 10. High energy charged particles (HZE) interact with matter by transferring energy to atomic electrons in a Coulomb process and by reacting with an atomic nucleus. Energy transferred in the first process increases with the square of the atomic number, so particles with high atomic numbers would be expected to lose large amounts of energy by this process. Nuclear reactions produced by (HZE) particles produce high-energy secondary particles which in turn lose energy to the material. The HZE nuclei are a major concern for radiation protection of humans during interplanetary missions because of the very high specific ionization of both primary and secondary particles. Computer codes have been developed to calculate the deposition of energy by very energetic charged particles in various materials. Calculations show that there is a significant buildup of secondary particles from nuclear fragmentation and Coulomb dissociation processes. A large portion of these particles are neutrons. Since neutrons carry no charge, they only lose energy by collision or reaction with a nucleus. Neutrons with high energies transfer large amounts of energy by inelastic collisions with nuclei. However, as the neutron energy decreases, elastic collisions become much more effective for energy loss. The lighter the nucleus, the greater the fraction of the neutron's kinetic energy that can be lost in an elastic collision. Thus, hydrogen-containing materials such as polymers are most effective in reducing the energy of neutrons. Once neutrons are reduced to very low energies, the probability for undergoing a reaction with a nucleus (the cross section) becomes very high. The product of such a reaction is often radioactive and can involve the release of a significant amount of energy. Thus, it is important to provide protection from low energy neutrons during a long duration space flight. Among the light elements, lithium and boron each have an isotope with a large thermal neutron capture cross section, Li-6 and B-10. However, B-10 is more abundant in the naturally-occurring element than Li-6, has a thermal neutron capture cross section four times that of Li-6, and produces the stable products, He-4 and Li-7 in the interaction while Li-6 produces radioactive tritium (H-3). Thus, boron is the best light-weight material for thermal neutron absorption in spacecraft. The work on this project was focused in two areas: computer design where existing computer codes were used, and in some cases modified, to calculate the propagation and interactions of high energy charged particles through various media, and materials development where boron was incorporated into high performance materials.

Atomic dynamics and the problem of the structural stability of free clusters of solidified inert gases

NASA Astrophysics Data System (ADS)

Verkhovtseva, É. T.; Gospodarev, I. A.; Grishaev, A. V.; Kovalenko, S. I.; Solnyshkin, D. D.; Syrkin, E. S.; Feodos'ev, S. B.

2003-05-01

The dependence of the rms amplitudes of atoms in free clusters of solidified inert gases on the cluster size is investigated theoretically and experimentally. Free clusters are produced by homogeneous nucleation in an adiabatically expanding supersonic stream. Electron diffraction is used to measure the rms amplitudes of the atoms; the Jacobi-matrix method is used for theoretical calculations. A series of distinguishing features of the atomic dynamics of microclusters was found. This was necessary to determine the character of the formation and the stability conditions of the crystal structure. It wass shown that for clusters consisting of less than N˜103 atoms, as the cluster size decreases, the rms amplitudes grow much more rapidly than expected from the increase in the specific contribution of the surface. It is also established that an fcc structure of a free cluster, as a rule, contains twinning defects (nuclei of an hcp phase). One reason for the appearance of such defects is the so-called vertex instability (anomalously large oscillation amplitudes) of the atoms in coordination spheres.

Magneto-structural correlations in dirhenium(iv) complexes possessing magnetic pathways with even or odd numbers of atoms.

PubMed

Pedersen, Anders H; Julve, Miguel; Martínez-Lillo, José; Cano, Joan; Brechin, Euan K

2017-09-12

The employment of pyrazine (pyz), pyrimidine (pym) and s-triazine (triz) ligands in Re IV chemistry leads to the isolation of a family of complexes of general formula (NBu 4 ) 2 [(ReX 5 ) 2 (μ-L)] (L = pyz, X = Cl (1) or Br (2); L = pym, X = Br (3); L = triz, X = Br (4)). 1-4 are dinuclear compounds where two pentahalorhenium(iv) fragments are connected by bidentate pyz, pym and triz ligands. Variable-temperature magnetic measurements, in combination with detailed theoretical studies, uncover the underlying magneto-structural correlation whereby the nature of the exchange between the metal ions is dictated by the number of intervening atoms. That is, the spin-polarization mechanism present dictates that odd and even numbers of atoms favour ferromagnetic (F) and antiferromagnetic (AF) exchange interactions, respectively. Hence, while the pyz ligand in 1 and 2 mediates AF coupling, the pym and triz ligands in 3 and 4 promote F interactions.

Isomer depletion as experimental evidence of nuclear excitation by electron capture

NASA Astrophysics Data System (ADS)

Chiara, C. J.; Carroll, J. J.; Carpenter, M. P.; Greene, J. P.; Hartley, D. J.; Janssens, R. V. F.; Lane, G. J.; Marsh, J. C.; Matters, D. A.; Polasik, M.; Rzadkiewicz, J.; Seweryniak, D.; Zhu, S.; Bottoni, S.; Hayes, A. B.; Karamian, S. A.

2018-02-01

The atomic nucleus and its electrons are often thought of as independent systems that are held together in the atom by their mutual attraction. Their interaction, however, leads to other important effects, such as providing an additional decay mode for excited nuclear states, whereby the nucleus releases energy by ejecting an atomic electron instead of by emitting a γ-ray. This ‘internal conversion’ has been known for about a hundred years and can be used to study nuclei and their interaction with their electrons. In the inverse process—nuclear excitation by electron capture (NEEC)—a free electron is captured into an atomic vacancy and can excite the nucleus to a higher-energy state, provided that the kinetic energy of the free electron plus the magnitude of its binding energy once captured matches the nuclear energy difference between the two states. NEEC was predicted in 1976 and has not hitherto been observed. Here we report evidence of NEEC in molybdenum-93 and determine the probability and cross-section for the process in a beam-based experimental scenario. Our results provide a standard for the assessment of theoretical models relevant to NEEC, which predict cross-sections that span many orders of magnitude. The greatest practical effect of the NEEC process may be on the survival of nuclei in stellar environments, in which it could excite isomers (that is, long-lived nuclear states) to shorter-lived states. Such excitations may reduce the abundance of the isotope after its production. This is an example of ‘isomer depletion’, which has been investigated previously through other reactions, but is used here to obtain evidence for NEEC.

Nuclear structure of the odd-neutron radon isotopes radon-203,205,207

NASA Astrophysics Data System (ADS)

Novak, John R.

High-spin states in the odd-neutron nuclei 203,205,207Rn have been investigated following heavy-ion fusion evaporation reaction experiments at Yale University, the University of Jyväskylä, and Argonne National Laboratory. The emitted gamma rays were measured at each location using the Jurosphere, YRAST Ball and Gammasphere detector arrays, respectively. Fusion products were detected at Jyväskylä using the gas-filled recoil separator RITU and at Argonne with the Fragment Mass Analyzer. Internal conversion electrons were measured at Argonne using the ICE Ball array of mini-orange spectrometers. Experiments that were carried out include excitation function measurements, multi-gamma coincidences, angular distribution measurements, polarization measurements, and internal conversion electron spectroscopy. No gamma-ray transitions above the 13/2+ state had been reported for any of these isotopes prior to this work. Nuclear decay schemes were constructed for 203,205,207Rn up to a spin of ~29/2ħ and an excitation energy of ~4 MeV. The states built on the 13/2 + isomers feature strongly in the decay of these nuclei. A roughly harmonic ΔI = 2 sequence assigned the ν( i13/2-1) configuration was observed in each odd-A nucleus. The energy level spacing of the 17/2+, 21/2+ and 25/2+ states relative to the 13/2 + state is similar to the 0+, 2+, 4 +, 6+ spacing observed in the neighboring even-even isotopes. The decreasing E(17/2+) energies and increasing R(/) /(/) values with decreasing neutron number reflect the increasing collectivity in the lighter isotopes as more neutron holes are added to the system. In contrast to the even-even neighbors, no evidence was found in any of the odd-A isotopes for isomeric states with lifetimes of tens of nanoseconds. An unobserved isomer in 205Rn with a lifetime of a few nanoseconds is suggested to exist near the top of the most intense cascade to account for the essentially isotropic angular distributions of the transitions in this sequence. A possible explanation for the lack of such long-lived isomers in the odd-A isotopes is the deformation-driving effects of the odd neutron, allowing additional configuration mixing and leading to increased collectivity at higher spin. A cascade of magnetic dipole transitions was observed in 205Rn and interpreted in terms of the shears mechanism. Its assigned configuration is the ν(i13/2-1) ⊗ π( i13/22). A short cascade of low-energy transitions was observed in 203Rn, but the shortness of the cascade and lack of other evidence precludes a shears band assignment for this sequence at this time. Such a band was not observed in 207Rn, which may be due to the fact that its core is not sufficiently polarized to allow the perpendicular coupling of the proton and neutron angular momentum vectors required for the manifestation of a shears band structure. A series of IBM and IBFM calculations were carried out in order to interpret the structure of the light radon nuclei in terms of a collective model. Excitation energies for the low-lying levels in the series of even- even isotopes 198-206Rn are well reproduced by the IBM predictions. Good agreement is also obtained between the IBFM calculations and the data obtained during the course of this work for the ΔI = 2 sequence built on the 13/2+ states in 203Rn and 205 Rn.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsuta, K.; Fukuda, M.; Tanigaki, M.

The magnetic moment of the proton drip-line nucleus {sup 9}C(I{sup {pi}}=3/2{sup -}, T{sub {1/2}}=126 ms) has been measured for the first time, using the {beta}-NMR detection technique with polarized radioactive beams. The measured value for the magnetic moment is {vert_bar} {mu}({sup 9}C) {vert_bar} = 1.3914{+-}0.0005 {mu}{sub N}. The deduced spin expectation value<{sigma}> of 1.44 is unusually larger than an other ones of even-odd nuclei.

Magnetic Moment of Proton Drip-Line Nucleus (9)C

NASA Technical Reports Server (NTRS)

Matsuta, K.; Fukuda, M.; Tanigaki, M.; Minamisono, T.; Nojiri, Y.; Mihara, M.; Onishi, T.; Yamaguchi, T.; Harada, A.; Sasaki, M.

1994-01-01

The magnetic moment of the proton drip-line nucleus C-9(I(sup (pi)) = 3/2, T(sub 1/2) = 126 ms) has been measured for the first time, using the beta-NMR detection technique with polarized radioactive beams. The measure value for the magnetic moment is 1mu(C-9)! = 1.3914 +/- 0.0005 (mu)N. The deduced spin expectation value of 1.44 is unusually larger than any other ones of even-odd nuclei.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Jing; Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of Education, Hunan Normal University, Changsha, Hunan 410081; Yu, Hongwei, E-mail: hwyu@hunnu.edu.cn

We study the spontaneous excitation of a detector (modeled by a two-level atom) in circular motion coupled nonlinearly to vacuum massless Rarita–Schwinger fields in the ultrarelativistic limit and demonstrate that the spontaneous excitation occurs for ground-state atoms in circular motion in vacuum but the excitation rate is not of a pure thermal form as that of the atoms in linear uniform acceleration. An interesting feature is that terms of odd powers in acceleration appear in the excitation rate whereas in the linear acceleration case there are only terms of even powers present. On the other hand, what makes the presentmore » case unique in comparison to the atom’s coupling to other fields that are previously studied is the appearance of the terms proportional to the seventh and ninth powers of acceleration in the mean rate of change of atomic energy which are absent in the scalar, electromagnetic and Dirac field cases. -- Highlights: •Circular Unruh effect for detector coupled to Rarita–Schwinger field. •Nonlinear coupling between the detector and the fields. •Detector in circular motion does not feel pure thermal bath. •Excitation rate contains terms of odd powers in acceleration.« less

Lorentz-like force emerging from kinematic interactions between electrons and nuclei in molecules: A quantum mechanical origin of symmetry breaking that can trigger molecular chirality.

PubMed

Takatsuka, Kazuo

2017-02-28

The Longuet-Higgins (Berry) phase arising from nonadiabatic dynamics and the Aharonov-Bohm phase associated with the dynamics of a charged particle in the electromagnetic vector potential are well known to be individually a manifestation of a class of the so-called geometrical phase. We herein discuss another similarity between the force working on a charged particle moving in a magnetic field, the Lorentz force, and a force working on nuclei while passing across a region where they have a strong quantum mechanical kinematic (nonadiabatic) coupling with electrons in a molecule. This kinematic force is indeed akin to the Lorentz force in that its magnitude is proportional to the velocity of the relevant nuclei and works in the direction perpendicular to its translational motion. Therefore this Lorentz-like nonadiabatic force is realized only in space of more or equal to three dimensions, thereby highlighting a truly multi-dimensional effect of nonadiabatic interaction. We investigate its physical significance qualitatively in the context of breaking of molecular spatial symmetry, which is not seen otherwise without this force. This particular symmetry breaking is demonstrated in application to a coplanar collision between a planar molecule and an atom sharing the same plane. We show that the atom is guided by this force to the direction out from the plane, resulting in a configuration that distinguishes one side of the mirror plane from the other. This can serve as a trigger for the dynamics towards molecular chirality.

Direct Observation of Two Proton Radioactivity Using Digital Photography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rykaczewski, Krzysztof Piotr; Pfutzner, M.; Dominik, Wojciech

2007-01-01

Recently the observation of a new type of spontaneous radioactive decay has been claimed in which two protons are simultaneously ejected by an atomic nucleus from the ground state1,2,3. Experimental data obtained for the extremely neutron-deficient nuclei 45Fe and 54Zn, were interpreted as the first evidence of such a decay mode which has been sought since 1960.4 However, the technique applied in those studies allowed only measurements of the decay time and the total energy released. Particles emitted in the decay were not identified and the conclusions had to be supported by theoretical arguments. Here we show for the firstmore » time, directly and unambiguously, that 45Fe indeed disintegrates by two-proton decay. Furthermore, we demonstrate that the decay branch of this isotope leads to various particle emission channels including two-proton and three-proton emission. To achieve this result we have developed a new type of detector V the Optical Time Projection Chamber (OTPC) in which digital photography is applied to nuclear physics for the first time. The detector records images of tracks from charged particles, allowing for their unambiguous identification and the reconstruction of decay events in three dimensions. This new and simple technique provides a powerful method to identify exotic decay channels involving emission of charged particles. It is expected that further studies with the OTPC device will yield important information on nuclei located at and beyond the proton drip-line, thus providing new material for testing and improving models of very unstable atomic nuclei.« less

Single-particle states vs. collective modes: friends or enemies ?

NASA Astrophysics Data System (ADS)

Otsuka, T.; Tsunoda, Y.; Togashi, T.; Shimizu, N.; Abe, T.

2018-05-01

The quantum self-organization is introduced as one of the major underlying mechanisms of the quantum many-body systems. In the case of atomic nuclei as an example, two types of the motion of nucleons, single-particle states and collective modes, dominate the structure of the nucleus. The collective mode arises as the balance between the effect of the mode-driving force (e.g., quadrupole force for the ellipsoidal deformation) and the resistance power against it. The single-particle energies are one of the sources to produce such resistance power: a coherent collective motion is more hindered by larger spacings between relevant single particle states. Thus, the single-particle state and the collective mode are "enemies" against each other. However, the nuclear forces are rich enough so as to enhance relevant collective mode by reducing the resistance power by changing single-particle energies for each eigenstate through monopole interactions. This will be verified with the concrete example taken from Zr isotopes. Thus, the quantum self-organization occurs: single-particle energies can be self-organized by (i) two quantum liquids, e.g., protons and neutrons, (ii) monopole interaction (to control resistance). In other words, atomic nuclei are not necessarily like simple rigid vases containing almost free nucleons, in contrast to the naïve Fermi liquid picture. Type II shell evolution is considered to be a simple visible case involving excitations across a (sub)magic gap. The quantum self-organization becomes more important in heavier nuclei where the number of active orbits and the number of active nucleons are larger.

From J. J. Thomson to FAIR, what do we learn from Large-Scale Mass and Half-Life Measurements of Bare and Few-Electron Ions?

NASA Astrophysics Data System (ADS)

Münzenberg, Gottfried; Geissel, Hans; Litvinov, Yuri A.

2010-04-01

This contribution is based on the combination of the talks: "What can we learn from large-scale mass measurements," "Present and future experiments with stored exotic nuclei at relativistic energies," and "Beta decay of highly-charged ions." Studying the nuclear mass surface gives information on the evolution of nuclear structure such as nuclear shells, the onset of deformation and the drip-lines. Previously, most of the masses far-off stability has been obtained from decay data. Modern methods allow direct mass measurements. They are much more sensitive, down to single atoms, access short-lived species and have high accuracy. Large-scale explorations of the nuclear mass surface are ideally performed with the combination of the in-flight FRagment Separator FRS and the Experimental Storage Ring ESR. After a brief historic introduction selected examples such as the evolution of shell closures far-off stability and the proton-neutron interaction will be discussed in the framework of our data. Recently, the experiments have been extended and led to the discovery of new heavy neutron-rich isotopes along with their mass and lifetime measurements. Storage rings applied at relativistic energies are a unique tool to study the radioactive decay of bare or few-electron atomic nuclei. New features observed with the analysis of stored circulating mother and daughter ions including oscillations in the decay curves of hydrogen-like nuclei will be addressed. Future experiments with NUSTAR at FAIR will further extend our knowledge to the borderlines of nuclear existence.

Measurement of the beta+ and orbital electron-capture decay rates in fully ionized, hydrogenlike, and heliumlike 140Pr ions.

PubMed

Litvinov, Yu A; Bosch, F; Geissel, H; Kurcewicz, J; Patyk, Z; Winckler, N; Batist, L; Beckert, K; Boutin, D; Brandau, C; Chen, L; Dimopoulou, C; Fabian, B; Faestermann, T; Fragner, A; Grigorenko, L; Haettner, E; Hess, S; Kienle, P; Knöbel, R; Kozhuharov, C; Litvinov, S A; Maier, L; Mazzocco, M; Montes, F; Münzenberg, G; Musumarra, A; Nociforo, C; Nolden, F; Pfützner, M; Plass, W R; Prochazka, A; Reda, R; Reuschl, R; Scheidenberger, C; Steck, M; Stöhlker, T; Torilov, S; Trassinelli, M; Sun, B; Weick, H; Winkler, M

2007-12-31

We report on the first measurement of the beta+ and orbital electron-capture decay rates of 140Pr nuclei with the simplest electron configurations: bare nuclei, hydrogenlike, and heliumlike ions. The measured electron-capture decay constant of hydrogenlike 140Pr58+ ions is about 50% larger than that of heliumlike 140Pr57+ ions. Moreover, 140Pr ions with one bound electron decay faster than neutral 140Pr0+ atoms with 59 electrons. To explain this peculiar observation one has to take into account the conservation of the total angular momentum, since only particular spin orientations of the nucleus and of the captured electron can contribute to the allowed decay.

Detection prospects of the cosmic neutrino background

NASA Astrophysics Data System (ADS)

Li, Yu-Feng

2015-04-01

The existence of the cosmic neutrino background (CνB) is a fundamental prediction of the standard Big Bang cosmology. Although current cosmological probes provide indirect observational evidence, the direct detection of the CνB in a laboratory experiment is a great challenge to the present experimental techniques. We discuss the future prospects for the direct detection of the CνB, with the emphasis on the method of captures on beta-decaying nuclei and the PTOLEMY project. Other possibilities using the electron-capture (EC) decaying nuclei, the annihilation of extremely high-energy cosmic neutrinos (EHECνs) at the Z-resonance, and the atomic de-excitation method are also discussed in this review (talk given at the International Conference on Massive Neutrinos, Singapore, 9-13 February 2015).

Measuring the Cosmic Particle Radiation from electrons to actinides - HNX/TIGERISS

NASA Astrophysics Data System (ADS)

Mitchell, John

2017-01-01

The Heavy Nuclei eXplorer (HNX) mission will measure the abundances of nuclei from Carbon (Z =6) to Curium (Z =96) in the cosmic radiation with the resolution to identify the atomic number of each detected nucleus. HNX will measure a significant number of actinides. HNX utilizes two high-precision instruments, the Extremely-heavy Cosmic-ray Composition Observer (ECCO) and the Cosmic-Ray Trans-Iron Galactic Element Recorder (CosmicTIGER), located in a SpaceX DragonLab capsule orbiting the Earth. This talk will discuss the motivating science, the HNX mission, the design and performance of the HNX instruments, and another new instrument, TIGERISS (Trans-Iron Galactic Element Recorder on the ISS), that will be proposed as an intermediate between SuperTIGER and HNX.

Quantum Gas Microscope for Fermionic Atoms

NASA Astrophysics Data System (ADS)

Okan, Melih; Cheuk, Lawrence; Nichols, Matthew; Lawrence, Katherine; Zhang, Hao; Zwierlein, Martin

2016-05-01

Strongly interacting fermions define the properties of complex matter throughout nature, from atomic nuclei and modern solid state materials to neutron stars. Ultracold atomic Fermi gases have emerged as a pristine platform for the study of many-fermion systems. In this poster we demonstrate the realization of a quantum gas microscope for fermionic 40 K atoms trapped in an optical lattice and the recent experiments which allows one to probe strongly correlated fermions at the single atom level. We combine 3D Raman sideband cooling with high- resolution optics to simultaneously cool and image individual atoms with single lattice site resolution at a detection fidelity above 95%. The imaging process leaves the atoms predominantly in the 3D motional ground state of their respective lattice sites, inviting the implementation of a Maxwell's demon to assemble low-entropy many-body states. Single-site resolved imaging of fermions enables the direct observation of magnetic order, time resolved measurements of the spread of particle correlations, and the detection of many-fermion entanglement. NSF, AFOSR-PECASE, AFOSR-MURI on Exotic Phases of Matter, ARO-MURI on Atomtronics, ONR, a Grant from the Army Research Office with funding from the DARPA OLE program, and the David and Lucile Packard Foundation.

Experimental determination of the field shift factor and the mass shift coefficient for the 1S0-3P1 spin-forbidden transition at 791 nm in neutral barium

NASA Astrophysics Data System (ADS)

Yu, Geng-Hua; Yan, Hui; Zhong, Jia-Qi; Liu, Hong; Zhu, Xiao-Ling; Yang, Wei

2018-01-01

The experimental measurements of the isotope shifts (ISs) for the 1S0-3P1 spin-forbidden transition at 791 nm in neutral barium have been carried out with a thermal barium atom beam. The hyperfine structure (HFS) constants a and b of the odd isotopes 137Ba and 135Ba for this transition have been extracted from the experimental results: a(137Ba) = 1149.9(1.0) MHz, b(137Ba)= -41.6(0.5) MHz, a(135Ba) = 1028.0(1.0) MHz, b(135Ba) = -27.5(0.5) MHz. The measured IS results with the reference isotope 138Ba are 183.7(1.0) MHz (137Ba-138Ba), 108.5(0.3) MHz (136Ba-138Ba) and 218.9(1.0) MHz (135Ba-138Ba). Our IS measurements are in good agreement with the previous experiments. The field shift (FS) factor Fk and the mass shift (MS) coefficient ΔKMS for this spin-forbidden transition have be determined experimentally as -3.19(4) GHz ṡ fm-2 and -242(20) GHz ṡ amu, respectively. The results provided herein could be used for further checks theoretically and experimentally, and could also contribute to the study on the nuclear structure of the barium isotopic nuclei.

Vibrational and rotational sequences in 101Mo and 103,4Ru studied via multinucleon transfer reactions

DOE PAGES

Regan, P. H.; Wheldon, C.; Yamamoto, A. D.; ...

2005-04-01

The near-yrast states of 42 101Mo 59 and 44 103,4Ru 59,60 have been studied following their population via heavy-ion multinucleon transfer reactions between a 136 Xe beam and a thin, self-supporting 100Mo target. The ground state sequence in 104Ru can be understood as demonstrating a simple evolution from a quasi-vibrational structure at lower spins to statically deformed, quasi-rotational excitation involving the population of a pair of low-Ω h 11/2 neutron orbitals. The effect of the decoupled h 11/2 orbital on this vibration-to-rotational evolution is demonstrated by an extension of the "E-GOS" prescription to include odd-A nuclei. The experimental results aremore » also compared with self-consistent Total Routhian Surface calculations which also highlight the polarising role of the highly aligned neutron h 11/2 orbital in these nuclei.« less

Science requirements for Heavy Nuclei Collection (HNC) experiment on NASA Long Duration Exposure Facility (LDEF) Mission 2

NASA Technical Reports Server (NTRS)

Price, P. Buford

1991-01-01

The Heavy Nuclei Collection (HNC) is a passive array of stacks of a special glass, 14 sheets thick, that record tracks of ultraheavy cosmic rays for later readout by automated systems on Earth. The primary goal is to determine the relative abundances of both the odd- and even-Z cosmic rays with Z equal to or greater than 50 with statistics a factor at least 60 greater than obtained in HEAO-3 and to obtain charge resolution at least as good as 0.25 charge unit. The secondary goal is to search for hypothetical particles such as superheavy elements. The HNC detector array will have a cumulative collection power equivalent to flying 32 sq m of detectors in space for 4 years. The array will be flown as a free-flight spacecraft and/or attached to Space Station Freedom.

A Nanotechnology Enhancement to Moore’s Law

DTIC Science & Technology

2013-01-01

suggested that quantummechanics may be playing a role in consciousness , if a quantum mechanical model of mind and consciousness was developed, this would...necessary enhancement by an increasingly maturing nanotechnology and facing the inevitable quantum -mechanical atomic and nuclei limits. Since we cannot...important. (ii) Quantum computing: The other types of transistor material are rapidly developed in laboratories worldwide, for example, Spintronics

Instrumentation for Applied Physics and Industrial Applications

NASA Astrophysics Data System (ADS)

Hillemanns, H.; Le Goff, J.-M.

This document is part of Part 2 'Principles and Methods' of Subvolume B 'Detectors for Particles and Radiation' of Volume 21 'Elementary Particles' of Landolt-Börnstein - Group I 'Elementary Particles, Nuclei and Atoms'. It contains the Section '7.3 Instrumentation for Applied Physics and Industrial Applications' of Chapter '7 Applications of Detectors in Technology; Medicine and Other Fields' with the content:

Three-Dimensional Nuclear Chart--Understanding Nuclear Physics and Nucleosynthesis in Stars

ERIC Educational Resources Information Center

Koura, Hiroyuki

2014-01-01

Three-dimensional (3D) nuclear charts were created using toy blocks, which represent the atomic masses per nucleon number and the total half-lives for each nucleus in the entire region of the nuclear mass. The bulk properties of the nuclei can be easily understood by using these charts. Subsequently, these charts were used in outreach activities…

The quantum universe

NASA Astrophysics Data System (ADS)

Hey, Anthony J. G.; Walters, Patrick

This book provides a descriptive, popular account of quantum physics. The basic topics addressed include: waves and particles, the Heisenberg uncertainty principle, the Schroedinger equation and matter waves, atoms and nuclei, quantum tunneling, the Pauli exclusion principle and the elements, quantum cooperation and superfluids, Feynman rules, weak photons, quarks, and gluons. The applications of quantum physics to astrophyics, nuclear technology, and modern electronics are addressed.

Approximate symmetries in atomic nuclei from a large-scale shell-model perspective

NASA Astrophysics Data System (ADS)

Launey, K. D.; Draayer, J. P.; Dytrych, T.; Sun, G.-H.; Dong, S.-H.

2015-05-01

In this paper, we review recent developments that aim to achieve further understanding of the structure of atomic nuclei, by capitalizing on exact symmetries as well as approximate symmetries found to dominate low-lying nuclear states. The findings confirm the essential role played by the Sp(3, ℝ) symplectic symmetry to inform the interaction and the relevant model spaces in nuclear modeling. The significance of the Sp(3, ℝ) symmetry for a description of a quantum system of strongly interacting particles naturally emerges from the physical relevance of its generators, which directly relate to particle momentum and position coordinates, and represent important observables, such as, the many-particle kinetic energy, the monopole operator, the quadrupole moment and the angular momentum. We show that it is imperative that shell-model spaces be expanded well beyond the current limits to accommodate particle excitations that appear critical to enhanced collectivity in heavier systems and to highly-deformed spatial structures, exemplified by the second 0+ state in 12C (the challenging Hoyle state) and 8Be. While such states are presently inaccessible by large-scale no-core shell models, symmetry-based considerations are found to be essential.

High-precision evaluation of the magnetic moment of the helion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neronov, Yu. I., E-mail: yineronov@mail.ru; Seregin, N. N.

NMR spectra of samples containing a mixture of hydrogen deuteride HD with pressure of about 80 atm and helium-3 with partial pressure of about 1 atm are analyzed. The ratio of the resonance frequencies of the nuclei, F({sup 3}He)/F(H{sub 2}), is determined to be 0.761786594(2), which is equal to the magnetic moment of the helion (bound in a helium atom) in the units of the magnetic moment of a proton (bound in molecular hydrogen). The uncertainty of two digits in the last place corresponds to a relative error of {delta}[F({sup 3}He)/F(H{sub 2})] = 2.6 Multiplication-Sign 10{sup -9}. The use ofmore » the known calculated data on the shielding of nuclei in the helium-3 atom ({sigma}({sup 3}He) = 59924(2) Multiplication-Sign 10{sup -9}) and on the shielding of protons in hydrogen ({sigma}(H{sub 2}) = 26288(2) Multiplication-Sign 10{sup -9}) yields a value of {mu}({sup 3}He)/{mu}{sub p} = -0.761812217(3) for the free magnetic moment of the helion in the units of the proton magnetic moment.« less

Emergent properties of nuclei from ab initio coupled-cluster calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hagen, G.; Hjorth-Jensen, M.; Jansen, G. R.

Emergent properties such as nuclear saturation and deformation, and the effects on shell structure due to the proximity of the scattering continuum and particle decay channels are fascinating phenomena in atomic nuclei. In recent years, ab initio approaches to nuclei have taken the first steps towards tackling the computational challenge of describing these phenomena from Hamiltonians with microscopic degrees of freedom. Our endeavor is now possible due to ideas from effective field theories, novel optimization strategies for nuclear interactions, ab initio methods exhibiting a soft scaling with mass number, and ever-increasing computational power. We review some of the recent accomplishments. We also present new results. The recently optimized chiral interaction NNLOmore » $${}_{{\\rm{sat}}}$$ is shown to provide an accurate description of both charge radii and binding energies in selected light- and medium-mass nuclei up to 56Ni. We derive an efficient scheme for including continuum effects in coupled-cluster computations of nuclei based on chiral nucleon–nucleon and three-nucleon forces, and present new results for unbound states in the neutron-rich isotopes of oxygen and calcium. Finally, the coupling to the continuum impacts the energies of the $${J}^{\\pi }=1/{2}^{-},3/{2}^{-},7/{2}^{-},3/{2}^{+}$$ states in $${}^{\\mathrm{17,23,25}}$$O, and—contrary to naive shell-model expectations—the level ordering of the $${J}^{\\pi }=3/{2}^{+},5/{2}^{+},9/{2}^{+}$$ states in $${}^{\\mathrm{53,55,61}}$$Ca.« less

Emergent properties of nuclei from ab initio coupled-cluster calculations

DOE PAGES

Hagen, G.; Hjorth-Jensen, M.; Jansen, G. R.; ...

2016-05-17

Emergent properties such as nuclear saturation and deformation, and the effects on shell structure due to the proximity of the scattering continuum and particle decay channels are fascinating phenomena in atomic nuclei. In recent years, ab initio approaches to nuclei have taken the first steps towards tackling the computational challenge of describing these phenomena from Hamiltonians with microscopic degrees of freedom. Our endeavor is now possible due to ideas from effective field theories, novel optimization strategies for nuclear interactions, ab initio methods exhibiting a soft scaling with mass number, and ever-increasing computational power. We review some of the recent accomplishments. We also present new results. The recently optimized chiral interaction NNLOmore » $${}_{{\\rm{sat}}}$$ is shown to provide an accurate description of both charge radii and binding energies in selected light- and medium-mass nuclei up to 56Ni. We derive an efficient scheme for including continuum effects in coupled-cluster computations of nuclei based on chiral nucleon–nucleon and three-nucleon forces, and present new results for unbound states in the neutron-rich isotopes of oxygen and calcium. Finally, the coupling to the continuum impacts the energies of the $${J}^{\\pi }=1/{2}^{-},3/{2}^{-},7/{2}^{-},3/{2}^{+}$$ states in $${}^{\\mathrm{17,23,25}}$$O, and—contrary to naive shell-model expectations—the level ordering of the $${J}^{\\pi }=3/{2}^{+},5/{2}^{+},9/{2}^{+}$$ states in $${}^{\\mathrm{53,55,61}}$$Ca.« less

Global and local approaches to population analysis: Bonding patterns in superheavy element compounds

NASA Astrophysics Data System (ADS)

Oleynichenko, Alexander; Zaitsevskii, Andréi; Romanov, Stepan; Skripnikov, Leonid V.; Titov, Anatoly V.

2018-03-01

Relativistic effective atomic configurations of superheavy elements Cn, Nh and Fl and their lighter homologues (Hg, Tl and Pb) in their simple compounds with fluorine and oxygen are determined using the analysis of local properties of molecular Kohn-Sham density matrices in the vicinity of heavy nuclei. The difference in populations of atomic spinors with the same orbital angular momentum and different total angular momenta is demonstrated to be essential for understanding the peculiarities of chemical bonding in superheavy element compounds. The results are fully compatible with those obtained by the relativistic iterative version of conventional projection analysis of global density matrices.

Odd-Z Transactinide Compound Nucleus Reactions Including the Discovery of 260Bh

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nelson, Sarah L.

Several reactions producing odd-Z transactinide compound nuclei were studiedwith the 88-Inch Cyclotron and the Berkeley Gas-Filled Separator at the Lawrence Berkeley National Laboratory. The goal was to produce the same compound nucleus ator near the same excitation energy with similar values of angular momentum via differentnuclear reactions. In doing so, it can be determined if there is a preference in entrancechannel, because under these experimental conditions the survival portion of Swiatecki, Siwek-Wilcznska, and Wilczynski's"Fusion By Diffusion" model is nearly identical forthe two reactions. Additionally, because the same compound nucleus is produced, theexit channel is the same. Four compound nuclei were examined in this study: 258Db, 262Bh, 266Mt, and 272Rg. These nuclei were produced by using very similar heavy-ion induced-fusion reactions which differ only by one proton in the projectile or target nucleus (e.g.: 50Ti + 209Bi vs. 51V + 208Pb). Peak 1n exit channel cross sections were determined for each reaction in each pair, and three of the four pairs' cross sections were identical within statistical uncertainties. This indicates there is not an obvious preference of entrancechannel in these paired reactions. Charge equilibration immediately prior to fusionleading to a decreased fusion barrier is the likely cause of this phenomenon. In addition to this systematic study, the lightest isotope of element 107, bohrium, was discovered in the 209Bi( 52Cr,n) reaction. 260Bh was found to decay by emission of a 10.16 MeV alpha particle with a half-life of 35more » $$+19\\atop{-9}$$ ms. The cross section is 59 pb at an excitation energy of 15.0 MeV. The effect of the N = 152 shell is also seen in this isotope's alpha particle energy, the first evidence of such an effect in Bh. All reactions studied are also compared to model predictions by Swiatecki, Siwek-Wilcznska, and Wilczynski 's" Fusion By Diffusion " theory.« less

pi-Selective stationary phases: (II) Adsorption behavior of substituted aromatic compounds on n-alkyl-phenyl stationary phases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gritti, Fabrice; Guiochon, Georges A; Mayfield, Kirsty

2010-01-01

The frontal analysis method was used to measure the adsorption isotherms of phenol, 4-chlorophenol, p-cresol, 4-methoxyphenol and caffeine on a series of columns packed with home-made alkyl-phenyl bonded silica particles. These ligands consist of a phenyl ring tethered to the silica support via a carbon chain of length ranging from 0 to 4 atoms. The adsorption isotherm models that fit best to the data account for solute-solute interactions that are likely caused by p-p interactions occurring between aromatic compounds and the phenyl group of the ligand. These interactions are the dominant factor responsible for the separation of low molecular weightmore » aromatic compounds on these phenyl-type stationary phases. The saturation capacities depend on whether the spacer of the ligands have an even or an odd number of carbon atoms, with the even alkyl chain lengths having a greater saturation capacity than the odd alkyl chain lengths. The trends in the adsorption equilibrium constant are also significantly different for the even and the odd chain length ligands.« less

Feasibility of a feedback control of atomic self-organization in an optical cavity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ivanov, D. A., E-mail: ivanov-den@yandex.ru; Ivanova, T. Yu.

Many interesting nonlinear effects are based on the strong interaction of motional degrees of freedom of atoms with an optical cavity field. Among them is the spatial self-organization of atoms in a pattern where the atoms group in either odd or even sites of the cavity-induced optical potential. An experimental observation of this effect can be simplified by using, along with the original cavity-induced feedback, an additional electronic feedback based on the detection of light leaking the cavity and the control of the optical potential for the atoms. Following our previous study, we show that this approach is more efficientmore » from the laser power perspective than the original scheme without the electronic feedback.« less

High resolution in-beam γ-ray spectroscopy

NASA Astrophysics Data System (ADS)

Kern, J.; Dousse, J.-Cl.; Gasser, M.; Perny, B.; Rhême, Ch.

1985-01-01

An in-beam curved crystal facility has been installed at the SIN variable energy cyclotron. Using the (110) planes of a 3.0 mm thick quartz lamina bent at 3.15 m, diffraction peaks typically 6 arcsec wide (FWHM) are obtained. The energy resolution is thus, for instance, 110 eV at 170 keV in 3rd order. Due to a sophisticated detector system and heavy shielding, the sensitivity of the instrument is quite good. The facility proves quite useful in (p,xnγ) reaction studies whenever the γ-ray spectrum is very complex, e.g. in the study of odd-odd deformed nuclei. Complicated multiplets appearing in the 176Yb(p,3nγ)174Lu spectrum could be successfully resolved. From the results we derive that the g-factors of the 142 d, Jπ=6- isomer, take anomalous values.

FROM THE HISTORY OF PHYSICS: The development of the first Soviet atomic bomb

NASA Astrophysics Data System (ADS)

Goncharov, German A.; Ryabev, Lev D.

2001-01-01

In the late 1930s and early 1940s, two remarkable physical phenomena — the fission of heavy nuclei and the chain fission reaction — were discovered, implying that a new powerful source of energy (nuclear fission energy) might become a practical possibility for mankind. At that time, however, the political situation in the world made the development of the atomic bomb the main objective of nuclear energy research in the countries involved. The first atomic bombs, notoriously used in the war against Japan, were produced by the United States of America only six and a half years after the discovery of fission. Four years later, the first Soviet atomic bomb was tested. This was a major step toward the establishment of nuclear parity which led to stability and global peace and thus greatly influenced the destiny of human kind. Based on documentary materials covering the period from 1939 to 1949, this paper traces the origin and evolution of the physical ideas behind the first Soviet atomic bomb and discusses the most important events associated with the project.

Superheavy-element spectroscopy: Correlations along element 115 decay chains

NASA Astrophysics Data System (ADS)

Rudolph, D.; Forsberg, U.; Sarmiento, L. G.; Golubev, P.; Fahlander, C.

2016-05-01

Following a brief summary of the region of the heaviest atomic nuclei yet created in the laboratory, data on more than hundred α-decay chains associated with the production of element 115 are combined to investigate time and energy correlations along the observed decay chains. Several of these are analysed using a new method for statistical assessments of lifetimes in sets of decay chains.

Tunable electronic structures of germanium monochalcogenide nanosheets via light non-metallic atom functionalization: a first-principles study.

PubMed

Ding, Yi; Wang, Yanli

2016-08-17

Germanium monochalcogenides, i.e. GeS and GeSe sheets, are isoelectronic analogues of phosphorene, which have been synthesized in recent experiments (P. Ramasamy et al., J. Mater. Chem. C, 2016, 4, 479). Utilizing first-principles calculations, we have investigated their tunable electronic and magnetic properties via light non-metallic atom (B, C, N, O, Si, P, S) functionalization. We find that on these GeS and GeSe sheets O and S adatoms prefer to locate at the top site above the Ge atom, while the other ones like to occupy the anion site, which push the original S/Se atom to the hollow site instead. O and S adatoms slightly affect the semiconducting behaviour of the doped systems, while B, C, N, Si, P ones will drastically modify their band structures and induce versatile spintronic properties. Through the supercell calculations, B and C adatoms are found to induce a bipolar semiconducting behaviour in the decorated systems, while the N/P adatom will cause a spin-gapless-semiconducting/nearly-half-metallic feature in them. The B/C/N/Si/P-substituted GeS/GeSe sheet can be formed by removing the hollow-site S/Se atom from the adatom-decorated structures, which exhibit an opposite semiconducting/metallic behaviour to their phosphorene counterparts. A general odd-even rule is proposed for this phenomenon, which shows that an odd (even) number of valence electron difference between the substitution and host atoms would cause a metallic (semiconducting) feature in the substituted systems. Our study demonstrates that atom functionalization is an efficient way to tailor the properties of GeS and GeSe nanosheets, which have adaptable electronic properties for potential applications in nanoelectronics and spintronics.

Nuclear Physics Around the Unitarity Limit.

PubMed

König, Sebastian; Grießhammer, Harald W; Hammer, H-W; van Kolck, U

2017-05-19

We argue that many features of the structure of nuclei emerge from a strictly perturbative expansion around the unitarity limit, where the two-nucleon S waves have bound states at zero energy. In this limit, the gross features of states in the nuclear chart are correlated to only one dimensionful parameter, which is related to the breaking of scale invariance to a discrete scaling symmetry and set by the triton binding energy. Observables are moved to their physical values by small perturbative corrections, much like in descriptions of the fine structure of atomic spectra. We provide evidence in favor of the conjecture that light, and possibly heavier, nuclei are bound weakly enough to be insensitive to the details of the interactions but strongly enough to be insensitive to the exact size of the two-nucleon system.

Rare isotopes and the sound of dilute nuclear matter

NASA Astrophysics Data System (ADS)

Papakonstantinou, P.

2018-04-01

Dilute baryonic matter, at densities below the normal saturation density of symmetric matter, is found on the crust of neutron stars and in collapsing supernova matter, its properties determining the evolution of those stellar objects. It is also readily found on the surface of ordinary and exotic atomic nuclei and lives fleetingly in the form of space-extended resonances of excited nucleons. Liminal states of nuclear matter, between saturation and full evaporation or clusterization, are manifest in the structure of symmetric nuclei through clustering and of very asymmetric rare species in haloes and the neutron skin; they stand literally at the threshold of a nucleus's response to hadronic probes, including processes which hinder or enable fusion. In this contribution I focus on excited states, and in particular exotic or not-so-exotic dipole excitation modes of N = Z nuclei and neutron-rich species, including new theoretical results on threshold strength. Modes of special interest are vibrations of and within diffuse surface layers and alpha-cluster oscillations. The modeling of such processes is relevant, directly or indirectly, for the description of reactions at astrophysical energies.

Infrared coronal emission lines and the possibility of their laser emission in Seyfert nuclei

NASA Technical Reports Server (NTRS)

Greenhouse, Matthew A.; Feldman, Uri; Smith, Howard A.; Klapisch, Marcel; Bhatia, Anand K.; Bar-Shalom, Avi

1993-01-01

Results are presented from detailed balance calculations, and a compilation of atomic data and other model calculations designed to support upcoming ISO and current observing programs involving IR coronal emission lines, together with a table with a complete line list of infrared transitions within the ground configurations 2s2 2p(k), 3s2 3p(k), and the first excited configurations 2s 2p and 3s 3p of highly ionized astrophysically abundant elements. The temperature and density parameter space for dominant cooling via IR coronal lines is presented, and the relationship of IR and optical coronal lines is discussed. It is found that, under physical conditions found in Seyfert nuclei, 14 of 70 transitions examined have significant population inversions in levels that give rise to IR coronal lines. Several IR coronal line transitions were found to have laser gain lengths that correspond to column densities of 10 exp 24-25/sq cm which are modeled to exist in Seyfert nuclei. Observations that can reveal inverted level populations and laser gain in IR coronal lines are suggested.

High-order above-threshold dissociation of molecules

NASA Astrophysics Data System (ADS)

Lu, Peifen; Wang, Junping; Li, Hui; Lin, Kang; Gong, Xiaochun; Song, Qiying; Ji, Qinying; Zhang, Wenbin; Ma, Junyang; Li, Hanxiao; Zeng, Heping; He, Feng; Wu, Jian

2018-03-01

Electrons bound to atoms or molecules can simultaneously absorb multiple photons via the above-threshold ionization featured with discrete peaks in the photoelectron spectrum on account of the quantized nature of the light energy. Analogously, the above-threshold dissociation of molecules has been proposed to address the multiple-photon energy deposition in the nuclei of molecules. In this case, nuclear energy spectra consisting of photon-energy spaced peaks exceeding the binding energy of the molecular bond are predicted. Although the observation of such phenomena is difficult, this scenario is nevertheless logical and is based on the fundamental laws. Here, we report conclusive experimental observation of high-order above-threshold dissociation of H2 in strong laser fields where the tunneling-ionized electron transfers the absorbed multiphoton energy, which is above the ionization threshold to the nuclei via the field-driven inelastic rescattering. Our results provide an unambiguous evidence that the electron and nuclei of a molecule as a whole absorb multiple photons, and thus above-threshold ionization and above-threshold dissociation must appear simultaneously, which is the cornerstone of the nowadays strong-field molecular physics.

Probing Long-Range Neutrino-Mediated Forces with Atomic and Nuclear Spectroscopy.

PubMed

Stadnik, Yevgeny V

2018-06-01

The exchange of a pair of low-mass neutrinos between electrons, protons, and neutrons produces a "long-range" 1/r^{5} potential, which can be sought for in phenomena originating on the atomic and subatomic length scales. We calculate the effects of neutrino-pair exchange on transition and binding energies in atoms and nuclei. In the case of atomic s-wave states, there is a large enhancement of the induced energy shifts due to the lack of a centrifugal barrier and the highly singular nature of the neutrino-mediated potential. We derive limits on neutrino-mediated forces from measurements of the deuteron binding energy and transition energies in positronium, muonium, hydrogen, and deuterium, as well as isotope-shift measurements in calcium ions. Our limits improve on existing constraints on neutrino-mediated forces from experiments that search for new macroscopic forces by 18 orders of magnitude. Future spectroscopy experiments have the potential to probe long-range forces mediated by the exchange of pairs of standard-model neutrinos and other weakly charged particles.

Probing Long-Range Neutrino-Mediated Forces with Atomic and Nuclear Spectroscopy

NASA Astrophysics Data System (ADS)

Stadnik, Yevgeny V.

2018-06-01

The exchange of a pair of low-mass neutrinos between electrons, protons, and neutrons produces a "long-range" 1 /r5 potential, which can be sought for in phenomena originating on the atomic and subatomic length scales. We calculate the effects of neutrino-pair exchange on transition and binding energies in atoms and nuclei. In the case of atomic s -wave states, there is a large enhancement of the induced energy shifts due to the lack of a centrifugal barrier and the highly singular nature of the neutrino-mediated potential. We derive limits on neutrino-mediated forces from measurements of the deuteron binding energy and transition energies in positronium, muonium, hydrogen, and deuterium, as well as isotope-shift measurements in calcium ions. Our limits improve on existing constraints on neutrino-mediated forces from experiments that search for new macroscopic forces by 18 orders of magnitude. Future spectroscopy experiments have the potential to probe long-range forces mediated by the exchange of pairs of standard-model neutrinos and other weakly charged particles.

Quantum conductance oscillation in linear monatomic silicon chains

NASA Astrophysics Data System (ADS)

Liu, Fu-Ti; Cheng, Yan; Yang, Fu-Bin; Chen, Xiang-Rong

2014-02-01

The conductance of linear silicon atomic chains with n=1-8 atoms sandwiched between Au electrodes is investigated by using the density functional theory combined with non-equilibrium Green's function. The results show that the conductance oscillates with a period of two atoms as the number of atoms in the chain is varied. We optimize the geometric structure of nanoscale junctions in different distances, and obtain that the average bond-length of silicon atoms in each chain at equilibrium positions is 2.15±0.03 Å. The oscillation of average Si-Si bond-length can explain the conductance oscillation from the geometric structure of atomic chains. We calculate the transmission spectrum of the chains in the equilibrium positions, and explain the conductance oscillation from the electronic structure. The transport channel is mainly contributed by px and py orbital electrons of silicon atoms. The even-odd oscillation is robust under external voltage up to 1.2 V.

Configuration and Spin Assignments of Yrast Band for Doubly Odd Nucleus 122Cs

NASA Astrophysics Data System (ADS)

Pu, Yun-wei; Wen, Jia-yan; Zhu, Shun-quan; Zheng, Ren-rong

1998-07-01

Energy spectrum of yrast band for 122Cs is studied by using particle-rotor model (PRM) of odd-odd nuclei, in which special attention is paid to the model basis accounting for the effect of the instability γ vibration perturbation around axial symmetry. In order to check the assignments of this band, two calculation schemes are put into practice. The first one is for previous πh11/2 otimes νg7/2 configuration with bandhead spin I0 = (6-) which was obtained from cranked shell model (CSM) calculation, and the other one is for πh11/2 otimes νh11/2 configuration with I0 = (9+) supported by the systematic analyses of experimental data. A qualitative comparison between the present PRM calculation and that of CSM has also been made. The results indicate that, rather than πh11/2 otimes νg7/2 with I0 = (6-), πh11/2 otimes νh11/2 with I0 = (9+) is a more reasonable assignment to the yrast band in 122Cs.

Probing the structural and electronic properties of cationic rubidium-gold clusters: [AunRb]+ (n = 1-10)

NASA Astrophysics Data System (ADS)

Zhao, Ya-Ru; Zhang, Hai-Rong; Qian, Yu; Duan, Xu-Chao; Hu, Yan-Fei

2016-03-01

Density functional theory has been applied to study the geometric structures, relative stabilities, and electronic properties of cationic [AunRb]+ and Aun + 1+ (n = 1-10) clusters. For the lowest energy structures of [AunRb]+ clusters, the planar to three-dimensional transformation is found to occur at cluster size n = 4 and the Rb atoms prefer being located at the most highly coordinated position. The trends of the averaged atomic binding energies, fragmentation energies, second-order difference of energies, and energy gaps show pronounced even-odd alternations. It indicated that the clusters containing odd number of atoms maintain greater stability than the clusters in the vicinity. In particular, the [Au6Rb]+ clusters are the most stable isomer for [AunRb]+ clusters in the region of n = 1-10. The charges in [AunRb]+ clusters transfer from the Rb atoms to Aun host. Density of states revealed that the Au-5d, Au-5p, and Rb-4p orbitals hardly participated in bonding. In addition, it is found that the most favourable channel of the [AunRb]+ clusters is Rb+ cation ejection. The electronic localisation function (ELF) analysis of the [AunRb]+ clusters shown that strong interactions are not revealed in this study.

Quantum self-organization and nuclear collectivities

NASA Astrophysics Data System (ADS)

Otsuka, T.; Tsunoda, Y.; Togashi, T.; Shimizu, N.; Abe, T.

2018-02-01

The quantum self-organization is introduced as one of the major underlying mechanisms of the quantum many-body systems. In the case of atomic nuclei as an example, two types of the motion of nucleons, single-particle states and collective modes, dominate the structure of the nucleus. The outcome of the collective mode is determined basically by the balance between the effect of the mode-driving force (e.g., quadrupole force for the ellipsoidal deformation) and the resistance power against it. The single-particle energies are one of the sources to produce such resistance power: a coherent collective motion is more hindered by larger gaps between relevant single particle states. Thus, the single-particle state and the collective mode are “enemies” each other. However, the nuclear forces are demonstrated to be rich enough so as to enhance relevant collective mode by reducing the resistance power by changing singleparticle energies for each eigenstate through monopole interactions. This will be verified with the concrete example taken from Zr isotopes. Thus, when the quantum self-organization occurs, single-particle energies can be self-organized, being enhanced by (i) two quantum liquids, e.g., protons and neutrons, (ii) two major force components, e.g., quadrupole interaction (to drive collective mode) and monopole interaction (to control resistance). In other words, atomic nuclei are not necessarily like simple rigid vases containing almost free nucleons, in contrast to the naïve Fermi liquid picture. Type II shell evolution is considered to be a simple visible case involving excitations across a (sub)magic gap. The quantum self-organization becomes more important in heavier nuclei where the number of active orbits and the number of active nucleons are larger. The quantum self-organization is a general phenomenon, and is expected to be found in other quantum systems.

Single-spin observables and orbital structures in hadronic distributions

NASA Astrophysics Data System (ADS)

Sivers, Dennis

2006-11-01

Single-spin observables in scattering processes (either analyzing powers or polarizations) are highly constrained by rotational invariance and finite symmetries. For example, it is possible to demonstrate that all single-spin observables are odd under the finite transformation O=PAτ where P is parity and Aτ is a finite symmetry that can be designated “artificial time reversal”. The operators P, O and Aτ all have eigenvalues ±1 so that all single-spin observables can be classified into two distinct categories: (1) P-odd and Aτ-even, (2) P-even and Aτ-odd. Within the light-quark sector of the standard model, P-odd observables are generated from pointlike electroweak processes while Aτ-odd observables (neglecting quark mass parameters) come from dynamic spin-orbit correlations within hadrons or within larger composite systems, such as nuclei. The effects of Aτ-odd dynamics can be inserted into transverse-momentum dependent constituent distribution functions and, in this paper, we construct the contribution from an orbital quark to the Aτ-odd quark parton distribution ΔNGq/p↑front(x,kTN;μ2). Using this distribution, we examine the crucial role of initial- and final-state interactions in the observation of the scattering asymmetries in different hard-scattering processes. This construction provides a geometrical and dynamical interpretation of the Collins conjugation relation between single-spin asymmetries in semi-inclusive deep inelastic scattering and the asymmetries in Drell-Yan production. Finally, our construction allows us to display a significant difference between the calculation of a spin asymmetry generated by a hard-scattering mechanism involving color-singlet exchange (such as a photon) and a calculation of an asymmetry with a hard-scattering exchange involving gluons. This leads to an appreciation of the process-dependence inherent in measurements of single-spin observables.

Gadolinium photoionization process

DOEpatents

Paisner, J.A.; Comaskey, B.J.; Haynam, C.A.; Eggert, J.H.

1993-04-13

A method is provided for selective photoionization of the odd-numbered atomic mass gadolinium isotopes 155 and 157. The selective photoionization is accomplished by circular or linear parallel polarized laser beam energy effecting a three-step photoionization pathway.

Gadolinium photoionization process

DOEpatents

Paisner, Jeffrey A.; Comaskey, Brian J.; Haynam, Christopher A.; Eggert, Jon H.

1993-01-01

A method is provided for selective photoionization of the odd-numbered atomic mass gadolinium isotopes 155 and 157. The selective photoionization is accomplished by circular or linear parallel polarized laser beam energy effecting a three-step photoionization pathway.

Microbial Incorporation of Fatty Acids Derived From n-Alkanes Into Glycerides and Waxes

PubMed Central

Davis, J. B.

1964-01-01

When n-alkanes with 13 to 20 carbon atoms were fed to a Nocardia closely related to N. salmonicolor, the produced cellular triglycerides and aliphatic waxes invariably contained fatty acids with an even or an odd number of carbon atoms subject to this feature of the n-alkane substrate. Beta-oxidation and C2 addition are both operative, as evidenced by the spectra of fatty acids incorporated into the cellular lipid components. There is no distinction in the rate of microbial incorporation of the odd-or even-numbered carbon chains. The fatty acids are apparently directly derived from the long chain n-alkanes, rather than synthesized via the classic C2-condensation route. The alcohol component of waxes produced by the Nocardia is invariably of the same chain length as the n-alkane substrate. PMID:14170957

Anomalous I-V curve for mono-atomic carbon chains

NASA Astrophysics Data System (ADS)

Song, Bo; Sanvito, Stefano; Fang, Haiping

2010-10-01

The electronic transport properties of mono-atomic carbon chains were studied theoretically using a combination of density functional theory and the non-equilibrium Green's functions method. The I-V curves for the chains composed of an even number of atoms and attached to gold electrodes through sulfur exhibit two plateaus where the current becomes bias independent. In contrast, when the number of carbon atoms in the chain is odd, the electric current simply increases monotonically with bias. This peculiar behavior is attributed to dimerization of the chains, directly resulting from their one-dimensional nature. The finding is expected to be helpful in designing molecular devices, such as carbon-chain-based transistors and sensors, for nanoscale and biological applications.

OH+ and H2O+: Probes of the Molecular Hydrogen Fraction and Cosmic-Ray Ionization Rate

NASA Astrophysics Data System (ADS)

Indriolo, Nick; Neufeld, D. A.; Gerin, M.; PRISMAS; WISH

2014-01-01

The fast ion-molecule chemistry that occurs in the interstellar medium (ISM) is initiated by cosmic-ray ionization of both atomic and molecular hydrogen. Species that are near the beginning of the network of interstellar chemistry such as the oxygen-bearing ions OH+ and H2O+ can be useful probes of the cosmic-ray ionization rate. This parameter is of particular interest as, to some extent, it controls the abundances of several molecules. Using observations of OH+ and H2O+ made with HIFI on board Herschel, we have inferred the cosmic-ray ionization rate of atomic hydrogen in multiple distinct clouds along 12 Galactic sight lines. These two molecules also allow us to determine the molecular hydrogen fraction (amount of hydrogen nuclei in H2 versus H) as OH+ and H2O+ abundances are dependent on the competition between dissociative recombination with electrons and hydrogen abstraction reactions involving H2. Our observations of OH+ and H2O+ indicate environments where H2 accounts for less than 10% of the available hydrogen nuclei, suggesting that these species primarily reside in the diffuse, atomic ISM. Average ionization rates in this gas are on the order of a few times 10-16 s-1, with most values in specific clouds above or below this average by a factor of 3 or so. This result is in good agreement with the most up-to-date determination of the distribution of cosmic-ray ionization rates in diffuse molecular clouds as inferred from observations of H3+.

Pressure dependence of side chain 13C chemical shifts in model peptides Ac-Gly-Gly-Xxx-Ala-NH2.

PubMed

Beck Erlach, Markus; Koehler, Joerg; Crusca, Edson; Munte, Claudia E; Kainosho, Masatsune; Kremer, Werner; Kalbitzer, Hans Robert

2017-10-01

For evaluating the pressure responses of folded as well as intrinsically unfolded proteins detectable by NMR spectroscopy the availability of data from well-defined model systems is indispensable. In this work we report the pressure dependence of 13 C chemical shifts of the side chain atoms in the protected tetrapeptides Ac-Gly-Gly-Xxx-Ala-NH 2 (Xxx, one of the 20 canonical amino acids). Contrary to expectation the chemical shifts of a number of nuclei have a nonlinear dependence on pressure in the range from 0.1 to 200 MPa. The size of the polynomial pressure coefficients B 1 and B 2 is dependent on the type of atom and amino acid studied. For H N , N and C α the first order pressure coefficient B 1 is also correlated to the chemical shift at atmospheric pressure. The first and second order pressure coefficients of a given type of carbon atom show significant linear correlations suggesting that the NMR observable pressure effects in the different amino acids have at least partly the same physical cause. In line with this observation the magnitude of the second order coefficients of nuclei being direct neighbors in the chemical structure also are weakly correlated. The downfield shifts of the methyl resonances suggest that gauche conformers of the side chains are not preferred with pressure. The valine and leucine methyl groups in the model peptides were assigned using stereospecifically 13 C enriched amino acids with the pro-R carbons downfield shifted relative to the pro-S carbons.

Ab initio Bogoliubov coupled cluster theory for open-shell nuclei

DOE PAGES

Signoracci, Angelo J.; Duguet, Thomas; Hagen, Gaute; ...

2015-06-29

Background: Ab initio many-body methods have been developed over the past 10 yr to address closed-shell nuclei up to mass A≈130 on the basis of realistic two- and three-nucleon interactions. A current frontier relates to the extension of those many-body methods to the description of open-shell nuclei. Several routes to address open-shell nuclei are currently under investigation, including ideas that exploit spontaneous symmetry breaking. Purpose: Singly open-shell nuclei can be efficiently described via the sole breaking of U(1) gauge symmetry associated with particle-number conservation as a way to account for their superfluid character. While this route was recently followed withinmore » the framework of self-consistent Green's function theory, the goal of the present work is to formulate a similar extension within the framework of coupled cluster theory. Methods: We formulate and apply Bogoliubov coupled cluster (BCC) theory, which consists of representing the exact ground-state wave function of the system as the exponential of a quasiparticle excitation cluster operator acting on a Bogoliubov reference state. Equations for the ground-state energy and the cluster amplitudes are derived at the singles and doubles level (BCCSD) both algebraically and diagrammatically. The formalism includes three-nucleon forces at the normal-ordered two-body level. The first BCC code is implemented in m scheme, which will permit the treatment of doubly open-shell nuclei via the further breaking of SU(2) symmetry associated with angular momentum conservation. Results: Proof-of-principle calculations in an N max=6 spherical harmonic oscillator basis for 16,18O and 18Ne in the BCCD approximation are in good agreement with standard coupled cluster results with the same chiral two-nucleon interaction, while 20O and 20Mg display underbinding relative to experiment. The breaking of U(1) symmetry, monitored by computing the variance associated with the particle-number operator, is relatively constant for all five nuclei, in both the Hartree-Fock-Bogoliubov and BCCD approximations. Conclusions: The newly developed many-body formalism increases the potential span of ab initio calculations based on single-reference coupled cluster techniques tremendously, i.e., potentially to reach several hundred additional midmass nuclei. The new formalism offers a wealth of potential applications and further extensions dedicated to the description of ground and excited states of open-shell nuclei. Short-term goals include the implementation of three-nucleon forces at the normal-ordered two-body level. Midterm extensions include the approximate treatment of triples corrections and the development of the equation-of-motion methodology to treat both excited states and odd nuclei. Long-term extensions include exact restoration of U(1) and SU(2) symmetries.« less

Nuclear Matter Properties with the Re-evaluated Coefficients of Liquid Drop Model

NASA Astrophysics Data System (ADS)

Chowdhury, P. Roy; Basu, D. N.

2006-06-01

The coefficients of the volume, surface, Coulomb, asymmetry and pairing energy terms of the semiempirical liquid drop model mass formula have been determined by furnishing best fit to the observed mass excesses. Slightly different sets of the weighting parameters for liquid drop model mass formula have been obtained from minimizations of \\chi 2 and mean square deviation. The most recent experimental and estimated mass excesses from Audi-Wapstra-Thibault atomic mass table have been used for the least square fitting procedure. Equation of state, nuclear incompressibility, nuclear mean free path and the most stable nuclei for corresponding atomic numbers, all are in good agreement with the experimental results.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mishev, S., E-mail: mishev@theor.jinr.ru; Voronov, V. V., E-mail: voronov@theor.jinr.ru

The role of the nucleon correlations in the ground states of even–even nuclei on the properties of low-lying states in odd–even spherical and transitional nuclei is studied. We reason about this subject using the language of the quasiparticle–phonon model which we extend to take account of the existence of quasiparticle⊗phonon configurations in the wave functions of the ground states of the even–even cores. Of paramount importance to the structure of the low-lying states happens to be the quasiparticle–phonon interaction in the ground states which we evaluated using both the standard and the extended random phase approximations. Numerical calculations for nucleimore » in the barium and cadmium regions are performed using pairing and quadrupole–quadrupole interaction modes which have the dominant impact on the lowest-lying states’ structure. It is found that states with same angular momentum and parity become closer in energy as compared to the predictions of models disregarding the backward amplitudes, which turns out to be in accord with the experimental data. In addition we found that the interaction between the last quasiparticle and the ground-state phonon admixtures produces configurations which contribute significantly to the magnetic dipolemoment of odd-A nuclei. It also reveals a potential for reproducing their experimental values which proves impossible if this interaction is neglected.« less

Theory of electronic structures and nuclear quadrupole interactions in molecular solids and semiconductor surfaces

NASA Astrophysics Data System (ADS)

Pati, Ranjit

We have investigated, using the Hartree-Fock Roothaan variational procedure, the electronic structures and associated nuclear quadrupole interactions (NQI) for the molecular solids, RDX (C3H6N6O6),/ /beta- HMX(C4H8N8O8), Cocaine (C17H21NO4), Cocaine Hydrochloride (C17H21NO4HCl) and Heroin (C21H23NO5) and for the (111) surface of silicon with adsorbed radioactive 111In atom and negative cadmium ion containing the excited nucleus 111Cd/* resulting from electron capture by lllIn. Our investigations indicate that for the ring 14N NQI parameters in RDX and β-HMX there is very good agreement between theory and experiment. For the peripheral 14N nuclei in NO2 groups, while the calculated electronic structures do explain the much weaker quadrupole coupling constants for these nuclei relative to the ring 14N nuclei, there are significant differences between theory and experiment. The influence of intermolecular interactions between adjacent molecules in the solid is invoked as a possible source for these differences. For the controlled substances, Cocaine and Heroin, again very good agreement is obtained between theory and experiment. For Cocaine Hydrochloride theory is able to explain the much smaller observed 14N nuclear quadrupole resonance frequency as compared to pure Cocaine. However there are significant differences between theory and experiment for the 14N and 35Cl quadrupole resonance frequencies. The influence of intermolecular interactions is one of the factors suggested to explain the difference. For the silicon (111) surface, the observed 111Cd/* NQI parameters, with the cadmium nucleus assumed to be located at the same site as the 111In nucleus from which it is generated, can be successfully explained by theory with the indium atom located at the two distinct sites available with the DAS model for the 7 x 7 reconstructed (111) surface. Some quantitative differences still remain, one of the main factor suggested for their explanation being a need for a thorough analysis of relaxation effects in the positions of silicon atoms associated with the presence of the indium atom. Applications of the Hartree-Fock Cluster theory to other related systems is suggested to subject the DAS model to additional tests at the microscopic level as in the system studied in the present thesis. (Abstract shortened by UMI.)

Combining X-ray and neutron crystallography with spectroscopy.

PubMed

Kwon, Hanna; Smith, Oliver; Raven, Emma Lloyd; Moody, Peter C E

2017-02-01

X-ray protein crystallography has, through the determination of the three-dimensional structures of enzymes and their complexes, been essential to the understanding of biological chemistry. However, as X-rays are scattered by electrons, the technique has difficulty locating the presence and position of H atoms (and cannot locate H + ions), knowledge of which is often crucially important for the understanding of enzyme mechanism. Furthermore, X-ray irradiation, through photoelectronic effects, will perturb the redox state in the crystal. By using single-crystal spectrophotometry, reactions taking place in the crystal can be monitored, either to trap intermediates or follow photoreduction during X-ray data collection. By using neutron crystallography, the positions of H atoms can be located, as it is the nuclei rather than the electrons that scatter neutrons, and the scattering length is not determined by the atomic number. Combining the two techniques allows much greater insight into both reaction mechanism and X-ray-induced photoreduction.

Electron quantum dynamics in atom-ion interaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sabzyan, H., E-mail: sabzyan@sci.ui.ac.ir; Jenabi, M. J.

2016-04-07

Electron transfer (ET) process and its dependence on the system parameters are investigated by solving two-dimensional time-dependent Schrödinger equation numerically using split operator technique. Evolution of the electron wavepacket occurs from the one-electron species hydrogen atom to another bare nucleus of charge Z > 1. This evolution is quantified by partitioning the simulation box and defining regional densities belonging to the two nuclei of the system. It is found that the functional form of the time-variations of these regional densities and the extent of ET process depend strongly on the inter-nuclear distance and relative values of the nuclear charges, whichmore » define the potential energy surface governing the electron wavepacket evolution. Also, the initial electronic state of the single-electron atom has critical effect on this evolution and its consequent (partial) electron transfer depending on its spreading extent and orientation with respect to the inter-nuclear axis.« less

Morphology and force probing of primary murine liver sinusoidal endothelial cells.

PubMed

Zapotoczny, B; Owczarczyk, K; Szafranska, K; Kus, E; Chlopicki, S; Szymonski, M

2017-07-01

Liver sinusoidal endothelial cells (LSECs) represent unique type of endothelial cells featured by their characteristic morphology, ie, lack of a basement membrane and presence of fenestrations-transmembrane pores acting as a dynamic filter between the vascular space and the liver parenchyma. Delicate structure of LSECs membrane combined with a submicron size of fenestrations hinders their visualization in live cells. In this work, we apply atomic force microscopy contact mode to characterize fenestrations in LSECs. We reveal the structure of fenestrations in live LSECs. Moreover, we show that the high-resolution imaging of fenestrations is possible for the glutaraldehyde-fixed LSECs. Finally, thorough information about the morphology of LSECs including great contrast in visualization of sieve plates and fenestrations is provided using Force Modulation mode. We show also the ability to precisely localize the cell nuclei in fixed LSECs. It can be helpful for more precise description of nanomechanical properties of cell nuclei using atomic force microscopy. Presented methodology combining high-quality imaging of fixed cells with an additional nanomechanical information of both live and fixed LSECs provides a unique approach to study LSECs morphology and nanomechanics that could foster understanding of the role of LSECs in maintaining liver homeostasis. Copyright © 2017 John Wiley & Sons, Ltd.

Neutron production by cosmic-ray muons in various materials

NASA Astrophysics Data System (ADS)

Manukovsky, K. V.; Ryazhskaya, O. G.; Sobolevsky, N. M.; Yudin, A. V.

2016-07-01

The results obtained by studying the background of neutrons produced by cosmic-raymuons in underground experimental facilities intended for rare-event searches and in surrounding rock are presented. The types of this rock may include granite, sedimentary rock, gypsum, and rock salt. Neutron production and transfer were simulated using the Geant4 and SHIELD transport codes. These codes were tuned via a comparison of the results of calculations with experimental data—in particular, with data of the Artemovsk research station of the Institute for Nuclear Research (INR, Moscow, Russia)—as well as via an intercomparison of results of calculations with the Geant4 and SHIELD codes. It turns out that the atomic-number dependence of the production and yield of neutrons has an irregular character and does not allow a description in terms of a universal function of the atomic number. The parameters of this dependence are different for two groups of nuclei—nuclei consisting of alpha particles and all of the remaining nuclei. Moreover, there are manifest exceptions from a power-law dependence—for example, argon. This may entail important consequences both for the existing underground experimental facilities and for those under construction. Investigation of cosmic-ray-induced neutron production in various materials is of paramount importance for the interpretation of experiments conducted at large depths under the Earth's surface.

Temperature dependence of stacking faults in catalyst-free GaAs nanopillars.

PubMed

Shapiro, Joshua N; Lin, Andrew; Ratsch, Christian; Huffaker, D L

2013-11-29

Impressive opto-electronic devices and transistors have recently been fabricated from GaAs nanopillars grown by catalyst-free selective-area epitaxy, but this growth technique has always resulted in high densities of stacking faults. A stacking fault occurs when atoms on the growing (111) surface occupy the sites of a hexagonal-close-pack (hcp) lattice instead of the normal face-centered-cubic (fcc) lattice sites. When stacking faults occur consecutively, the crystal structure is locally wurtzite instead of zinc-blende, and the resulting band offsets are known to negatively impact device performance. Here we present experimental and theoretical evidence that indicate stacking fault formation is related to the size of the critical nucleus, which is temperature dependent. The difference in energy between the hcp and fcc orientation of small nuclei is computed using density-function theory. The minimum energy difference of 0.22 eV is calculated for a nucleus with 21 atoms, so the population of nuclei in the hcp orientation is expected to decrease as the nucleus grows larger. The experiment shows that stacking fault occurrence is dramatically reduced from 22% to 3% by raising the growth temperature from 730 to 790 ° C. These data are interpreted using classical nucleation theory which dictates a larger critical nucleus at higher growth temperature.

New Mechanism of Low Energy Nuclear Reactions Using Superlow

NASA Astrophysics Data System (ADS)

Gareev, F. A.; Zhidkova, I. E.

2006-03-01

We proposed a new mechanism of LENR (low energy nuclear reactions) cooperative processes in the whole system - nuclei+atoms+condensed matter can occur at smaller threshold than the corresponding ones assoiciated with free constituents. The cooperative processes can be induced and enhanced by (``superlow energy'') external fields. The excess heat is the emission of internal energy, and transmutations from LENR are the result of redistribution of the internal energy of the whole system. A review of possible stimulation mechanisms of LENR is presented. We have concluded that transmutation of nuclei at low energies and excess heat are possible in the framework of the known fundamental physical laws: The universal resonance synchronization principle, and based on it, different enhancement mechanisms of reaction rates are responsible for these processes. The excitation and ionization of atoms may play the role of a trigger for LENR. F.A. Gareev, I.E. Zhidkova, E-print arXiv Nucl-th/0511092 v1 30 Nov 2005. F.A. Gareev, In: FPB-98, Novosibirsk, June 1998, p.92; F.A.Gareev, G.F. Gareeva, in: Novosibirsk, July 2000, p.161. F.A. Gareev, I.E. Zhidkova and Yu.L. Ratis, Preprint JINR P4-2004-68, Dubna, 2004. F.A. Gareev, I.E. Zhidkova, E-print arXiv Nucl-th/0505021 9 May 2005.

Understanding the crystallization behavior of as-deposited Ti-Sb-Te alloys through real-time radial distribution functions.

PubMed

Zhu, Min; Xia, Mengjiao; Song, Zhitang; Cheng, Yan; Wu, Liangcai; Rao, Feng; Song, Sannian; Wang, Miao; Lu, Yegang; Feng, Songlin

2015-06-07

Phase change materials, successfully used in optical data-storage and non-volatile electronic memory, are well-known for their ultrafast crystallization speed. However, the fundamental understanding of their crystallization behavior, especially the nucleation process, is limited by present experimental techniques. Here, real-time radial distribution functions (RDFs), derived from the selected area electron diffractions, are employed as structural probes to comprehensively study both nucleation and subsequent growth stages of Ti-doped Sb2Te3 (TST) materials in the electron-irradiation crystallization process. It can be found that the incorporation of Ti atoms in Sb2Te3 forms wrong bonds such as Ti-Te, Ti-Sb, breaks the originally ordered atomic arrangement and diminishes the initial nucleus size of the as-deposited films, which results in better thermal stability. But these nuclei hardly grow until their sizes exceed a critical value, and then a rapid growth period starts. This means that an extended nucleation time is required to form the supercritical nuclei of TST alloys with higher concentration. Also, the increasing formation of four-membered rings, which served as nucleation sites, after doping excessive Ti is responsible for the change of the crystallization behavior from growth-dominated to nucleation-dominated.

Decay of excited nuclei produced in (78,82)Kr+(40)Ca reactions at 5.5 MeV/nucleon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gomez Del Campo, Jorge; Ademard, G.; Wieleczko, J. P.

2011-01-01

Decay modes of excited nuclei are investigated in {sup 78,82}Kr+{sup 40}Ca reactions at 5.5 MeV/nucleon. Charged products were measured by means of the 4{pi} INDRA array. Kinetic-energy spectra and angular distributions of fragments with atomic number 3 {le} Z {le} 28 indicate a high degree of relaxation and are compatible with a fissionlike phenomenon. Persistence of structure effects is evidenced from elemental cross sections ({sigma}{sub Z}) as well as a strong odd-even staggering (o-e-s) of the light-fragment yields. The magnitude of the staggering does not significantly depend on the neutron content of the emitting system. Fragment-particle coincidences suggest that themore » light partners in very asymmetric fission are emitted either cold or at excitation energies below the particle emission thresholds. The evaporation residue cross section of the {sup 78}Kr+{sup 40}Ca reaction is slightly higher than the one measured in the {sup 82}Kr+{sup 40}Ca reaction. The fissionlike component is larger by {approx}25% for the reaction having the lowest neutron-to-proton ratio. These experimental features are confronted to the predictions of theoretical models. The Hauser-Feshbach approach including the emission of fragments up to Z = 14 in their ground states as well as excited states does not account for the main features of {sigma}{sub Z}. For both reactions, the transition-state formalism reasonably reproduces the Z distribution of the fragments with charge 12 {le} Z {le} 28. However, this model strongly overestimates the light-fragment cross sections and does not explain the o-e-s of the yields for 6 {le} Z {le} 10. The shape of the whole Z distribution and the o-e-s of the light-fragment yields are satisfactorily reproduced within the dinuclear system framework which treats the competition among evaporation, fusion-fission, and quasifission processes. The model suggests that heavy fragments come mainly from quasifission while light fragments are predominantly populated by fusion. An underestimation of the cross sections for 16 {le} Z {le} 22 could signal a mechanism in addition to the capture process.« less

Striatal dysfunction increases basal ganglia output during motor cortex activation in parkinsonian rats.

PubMed

Belluscio, Mariano A; Riquelme, Luis A; Murer, M Gustavo

2007-05-01

During movement, inhibitory neurons in the basal ganglia output nuclei show complex modulations of firing, which are presumptively driven by corticostriatal and corticosubthalamic input. Reductions in discharge should facilitate movement by disinhibiting thalamic and brain stem nuclei while increases would do the opposite. A proposal that nigrostriatal dopamine pathway degeneration disrupts trans-striatal pathways' balance resulting in sustained overactivity of basal ganglia output nuclei neurons and Parkinson's disease clinical signs is not fully supported by experimental evidence, which instead shows abnormal synchronous oscillatory activity in animal models and patients. Yet, the possibility that variation in motor cortex activity drives transient overactivity in output nuclei neurons in parkinsonism has not been explored. In Sprague-Dawley rats with 6-hydroxydopamine (6-OHDA)-induced nigrostriatal lesions, approximately 50% substantia nigra pars reticulata (SNpr) units show abnormal cortically driven slow oscillations of discharge. Moreover, these units selectively show abnormal responses to motor cortex stimulation consisting in augmented excitations of an odd latency, which overlapped that of inhibitory responses presumptively mediated by the trans-striatal direct pathway in control rats. Delivering D1 or D2 dopamine agonists into the striatum of parkinsonian rats by reverse microdialysis reduced these abnormal excitations but had no effect on pathological oscillations. The present study establishes that dopamine-deficiency related changes of striatal function contribute to producing abnormally augmented excitatory responses to motor cortex stimulation in the SNpr. If a similar transient overactivity of basal ganglia output were driven by motor cortex input during movement, it could contribute to impeding movement initiation or execution in Parkinson's disease.

Magnetic rotation (MR) band-crossing at high spin states: Role of nucleons in this crossing in N = 78 odd-Z isotones

NASA Astrophysics Data System (ADS)

Kumar, Suresh; Garg, Ritika; Mandal, Samit Kumar

2013-02-01

Magnetic-dipole rotational (MR) bands were discovered about 15 years ago, and have been explained using shears mechanism. The theoretical understanding of these bands has been provided using tilted axis cranking (TAC). At present, magnetic rotation has been seen in whole nuclear landscape and about 180 bands in 80 nuclides has been observed in mass regions A=20, 60, 80, 110, 135 and 195 respectively. The crossing of these bands (ΔI = 1) is very much similar to normal band crossing (ΔI = 2) and already exhibited in different mass regions. We have observed new MR bands and their crossing in the A = 130 mass region in 135La, 137Pr and 139Pm nuclei. The systematic evolution of this phenomenon in N=78 odd-Z isotones leads us to understand the role on nucleons in this crossing.

Search For ɛ-Bound Nuclei

NASA Astrophysics Data System (ADS)

Machner, H.

2011-10-01

The η meson can be bound to atomic nuclei. Experimental search is discussed in the form of final state interaction for the reactions dp→3Heη and dd→4Heη. For the latter case tensor polarized deuterons were used in order to extract the s-wave strength. For both reactions complex scattering lengths are deduced: In a two-nucleon transfer reaction under quasi-free conditions, p27Al→3HeX, was investigated. The system X can be the bound 25Mg⊗η at rest. When a possible decay of an intermediate N*(1535) is required, a highly significant bump shows up in the missing mass spectrum. The data give for a bound state a binding energy of 13.3±1.6 MeV and a width of σ = 4.4±1.3 MeV.

Nuclear Physics Around the Unitarity Limit

DOE PAGES

König, Sebastian; Grießhammer, Harald W.; Hammer, H. -W.; ...

2017-05-15

We argue that many features of the structure of nuclei emerge from a strictly perturbative expansion around the unitarity limit, where the two-nucleon S waves have bound states at zero energy. In this limit, the gross features of states in the nuclear chart are correlated to only one dimensionful parameter, which is related to the breaking of scale invariance to a discrete scaling symmetry and set by the triton binding energy. Observables are moved to their physical values by small perturbative corrections, much like in descriptions of the fine structure of atomic spectra. We provide evidence in favor of themore » conjecture that light, and possibly heavier, nuclei are bound weakly enough to be insensitive to the details of the interactions but strongly enough to be insensitive to the exact size of the two-nucleon system.« less

Cosmic-ray energy spectra between 10 and several hundred GeV per atomic mass unit for elements from Ar-18 to Ni-28 - Results from HEAO 3

NASA Technical Reports Server (NTRS)

Binns, W. R.; Israel, M. H.; Jones, Michael D.; Kamionkowski, M. P.; Garrard, T. L.

1988-01-01

Results from the Heavy Nuclei experiment on HEAO 3 are used to determine the primary abundances of Ni and Fe. Ni and Fe are found to have nearly constant relative abundances over the interval of 10 to about 500 GeV per amu. Individual secondary elements derived principally from interactions of primary Fe nuclei are shown to display a power-law decrease in relative abundance up to about 150 GeV per amu. Ar/Fe and Ca/Fe ratios of 2.6 + or - 0.7 percent and 8.8 + or - 0.7 percent, respectively, are found, confirming a fractionation of source abundances in which elements with high values of the first ionization potential are depleted relative to those with low first ionization potential.

Neutrino-nucleus scattering of {sup 95,97}Mo and {sup 116}Cd

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ydrefors, E.; Almosly, W.; Suhonen, J.

2013-12-30

Accurate knowledge about the nuclear responses to supernova neutrinos for relevant nuclear targets is important both for neutrino detection and for astrophysical applications. In this paper we discuss the cross sections for the charged-current neutrino-nucleus scatterings off {sup 95,97}Mo and {sup 116}Cd. The microscopic quasiparticle-phonon model is adopted for the odd-even nuclei {sup 95,97}Mo. In the case of {sup 116}Cd we present cross sections both for the Bonn one-boson-exchange potential and self-consistent calculations based on modern Skyrme interactions.

Weak-interaction rates in stellar conditions

NASA Astrophysics Data System (ADS)

Sarriguren, Pedro

2018-05-01

Weak-interaction rates, including β-decay and electron captures, are studied in several mass regions at various densities and temperatures of astrophysical interest. In particular, we study odd-A nuclei in the pf-shell region, which are involved in presupernova formations. Weak rates are relevant to understand the late stages of the stellar evolution, as well as the nucleosynthesis of heavy nuclei. The nuclear structure involved in the weak processes is studied within a quasiparticle proton-neutron random-phase approximation with residual interactions in both particle-hole and particle-particle channels on top of a deformed Skyrme Hartree-Fock mean field with pairing correlations. First, the energy distributions of the Gamow-Teller strength are discussed and compared with the available experimental information, measured under terrestrial conditions from charge-exchange reactions. Then, the sensitivity of the weak-interaction rates to both astrophysical densities and temperatures is studied. Special attention is paid to the relative contribution to these rates of thermally populated excited states in the decaying nucleus and to the electron captures from the degenerate electron plasma.

Total angular momenta of high-lying odd levels of U I at ∼ 4 eV using resonance ionization laser polarization spectroscopy

NASA Astrophysics Data System (ADS)

Rath, Asawari D.; Kundu, S.; Ray, A. K.

2018-02-01

Laser induced photoionization of atoms shows significant dependence on the choice of polarizations of lasers. In multi-step, multi-photon excitation and subsequent ionization of atoms different polarization combinations of the exciting lasers lead to distinctly different ion yields. This fact is exploited in this work to determine total angular momenta of odd-parity energy levels of U I lying at ∼ 4 eV from its ground level using resonance ionization laser polarization spectroscopy in time of flight mass spectrometer. These levels are populated by two-step resonant excitation using two pulsed dye lasers with preset polarizations of choice followed by nonresonant ionization by third laser. The dependence of ionization yield on specific polarizations of the first two lasers is studied experimentally for each level under consideration. This dependence when compared to simulations makes possible unambiguous assignment of J angular momenta to these levels.

Attosecond control of orbital parity mix interferences and the relative phase of even and odd harmonics in an attosecond pulse train.

PubMed

Laurent, G; Cao, W; Li, H; Wang, Z; Ben-Itzhak, I; Cocke, C L

2012-08-24

We experimentally demonstrate that atomic orbital parity mix interferences can be temporally controlled on an attosecond time scale. Electron wave packets are formed by ionizing argon gas with a comb of odd and even high-order harmonics, in the presence of a weak infrared field. Consequently, a mix of energy-degenerate even and odd parity states is fed in the continuum by one- and two-photon transitions. These interfere, leading to an asymmetric electron emission along the polarization vector. The direction of the emission can be controlled by varying the time delay between the comb and infrared field pulses. We show that such asymmetric emission provides information on the relative phase of consecutive odd and even order harmonics in the attosecond pulse train.

DAMQT: A package for the analysis of electron density in molecules

NASA Astrophysics Data System (ADS)

López, Rafael; Rico, Jaime Fernández; Ramírez, Guillermo; Ema, Ignacio; Zorrilla, David

2009-09-01

DAMQT is a package for the analysis of the electron density in molecules and the fast computation of the density, density deformations, electrostatic potential and field, and Hellmann-Feynman forces. The method is based on the partition of the electron density into atomic fragments by means of a least deformation criterion. Each atomic fragment of the density is expanded in regular spherical harmonics times radial factors, which are piecewise represented in terms of analytical functions. This representation is used for the fast evaluation of the electrostatic potential and field generated by the electron density and nuclei, as well as for the computation of the Hellmann-Feynman forces on the nuclei. An analysis of the atomic and molecular deformations of the density can be also carried out, yielding a picture that connects with several concepts of the empirical structural chemistry. Program summaryProgram title: DAMQT1.0 Catalogue identifier: AEDL_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEDL_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GPLv3 No. of lines in distributed program, including test data, etc.: 278 356 No. of bytes in distributed program, including test data, etc.: 31 065 317 Distribution format: tar.gz Programming language: Fortran90 and C++ Computer: Any Operating system: Linux, Windows (Xp, Vista) RAM: 190 Mbytes Classification: 16.1 External routines: Trolltech's Qt (4.3 or higher) ( http://www.qtsoftware.com/products), OpenGL (1.1 or higher) ( http://www.opengl.org/), GLUT 3.7 ( http://www.opengl.org/resources/libraries/glut/). Nature of problem: Analysis of the molecular electron density and density deformations, including fast evaluation of electrostatic potential, electric field and Hellmann-Feynman forces on nuclei. Solution method: The method of Deformed Atoms in Molecules, reported elsewhere [1], is used for partitioning the molecular electron density into atomic fragments, which are further expanded in spherical harmonics times radial factors. The partition is used for defining molecular density deformations and for the fast calculation of several properties associated to density. Restrictions: The current version is limited to 120 atoms, 2000 contracted functions, and l=5 in basis functions. Density must come from a LCAO calculation (any level) with spherical (not Cartesian) Gaussian functions. Unusual features: The program contains an OPEN statement to binary files (stream) in file GOPENMOL.F90. This statement has not a standard syntax in Fortran 90. Two possibilities are considered in conditional compilation: Intel's ifort and Fortran2003 standard. This latter is applied to compilers other than ifort (gfortran uses this one, for instance). Additional comments: The distribution file for this program is over 30 Mbytes and therefore is not delivered directly when download or e-mail is requested. Instead a html file giving details of how the program can be obtained is sent. Running time: Largely dependent on the system size and the module run (from fractions of a second to hours). References: [1] J. Fernández Rico, R. López, I. Ema, G. Ramírez, J. Mol. Struct. (Theochem) 727 (2005) 115.

Development of a collinear laser spectrometer facility at VECC: First test result

NASA Astrophysics Data System (ADS)

Ali, Md Sabir; Ray, Ayan; Raja, Waseem; Bandyopadhyay, Arup; Naik, Vaishali; Polley, Asish; Chakrabarti, Alok

2018-04-01

We report here the development of collinear laser spectroscopy (CLS) system at VECC for the study of hyperfine spectrum and isotopic shift of stable and unstable isotopes. The facility is first of its kind in the country allowing measurement of hyperfine splitting of atomic levels using atomic beams. The CLS system is installed downstream of the focal plane of the existing isotope separator online (ISOL) facility at VECC and is recently commissioned by successfully resolving the fluorescence spectrum of the hyperfine levels in ^{85,87}Rb. The atomic beams of Rb were produced by charge exchange of 8 keV Rb ion beam which were produced, extracted and transported to the charge exchange cell using the ion sources, extractor and the beam-line magnets of the ISOL facility. The laser propagating opposite to the ion / atom beam direction was allowed to interact with the atom beam and fluorescence spectrum was recorded. The experimental set-up and the experiment conducted are reported in detail. The measures needed to be carried out for improving the sensitivity to a level necessary for studying short-lived exotic nuclei have also been discussed.

Ultrasonic atomization of tissue and its role in tissue fractionation by high intensity focused ultrasound

PubMed Central

Simon, Julianna C.; Sapozhnikov, Oleg A.; Khokhlova, Vera A.; Wang, Yak-Nam; Crum, Lawrence A.; Bailey, Michael R.

2012-01-01

Atomization and fountain formation is a well-known phenomenon that occurs when a focused ultrasound wave in liquid encounters an air interface. High intensity focused ultrasound (HIFU) has been shown to fractionate tissue into submicron-size fragments in a process termed boiling histotripsy, wherein the focused ultrasound wave superheats the tissue at the focus, producing a millimetre-size boiling or vapour bubble in several milliseconds. Yet the question of how this millimetre-size boiling bubble creates submicron-size tissue fragments remains. The hypothesis of this work is that tissue can behave as a liquid such that it forms a fountain and atomization within the vapour bubble produced in boiling histotripsy. We describe an experiment, in which a 2-MHz HIFU transducer (maximum in situ intensity of 24,000 W/cm2) was aligned with an air-tissue interface meant to simulate the boiling bubble. Atomization and fountain formation were observed with high-speed photography and resulted in tissue erosion. Histological examination of the atomized tissue showed whole and fragmented cells and nuclei. Air-liquid interfaces were also filmed. Our conclusion was that HIFU can fountain and atomize tissue. Although this process does not entirely mimic what was observed in liquids, it does explain many aspects of tissue fractionation in boiling histotripsy. PMID:23159812

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Rong; Wu, Yongquan, E-mail: yqwu@shu.edu.cn; Xiao, Junjiang

We observed homogeneous nucleation process of supercooled liquid Fe by molecular dynamics simulations. Using bond-orientational order parameters together with Voronoi polyhedron method, we characterized local structure, calculated the volume of Voronoi polyhedra of atoms and identified the structure and density fluctuations. We monitored the formation of nucleus and analyzed its inner structure. The birth and growth of the pre-nucleus and nucleus are accompanied with aggregating and disaggregating processes in the time scale of femtosecond. Only the initial solid-like clusters (ISLC), ranging from 1 to 7 atoms, pop up directly from liquid. The relation between the logarithm of number of clustersmore » and the cluster size was found to be linear for ISLCs and was observed to be parabolic for all solid-like clusters (SLC) due to aggregating and disaggregating effects. The nucleus and pre-nuclei mainly consist of body centered cubic (BCC) and hexagonal close packed atoms, while the BCC atoms tend to be located at the surface. Medium-range structure fluctuations induce the birth of ISLCs, benefit the aggregation of embryos and remarkably promote the nucleation. But density fluctuations contribute little to nucleation. The lifetime of most icosahedral-like atoms (ICO) is shorter than 0.7 ps. No obvious relationship was found between structure/density fluctuations and the appearance of ICO atoms.« less

Current Status of Nuclear Physics Research

NASA Astrophysics Data System (ADS)

Bertulani, Carlos A.; Hussein, Mahir S.

2015-12-01

In this review, we discuss the current status of research in nuclear physics which is being carried out in different centers in the world. For this purpose, we supply a short account of the development in the area which evolved over the last nine decades, since the discovery of the neutron. The evolution of the physics of the atomic nucleus went through many stages as more data became available. We briefly discuss models introduced to discern the physics behind the experimental discoveries, such as the shell model, the collective model, the statistical model, the interacting boson model, etc., some of these models may be seemingly in conflict with each other, but this was shown to be only apparent. The richness of the ideas and abundance of theoretical models attests to the important fact that the nucleus is a really singular system in the sense that it evolves from two-body bound states such as the deuteron, to few-body bound states, such as 4He, 7Li, 9Be, etc. and up the ladder to heavier bound nuclei containing up to more than 200 nucleons. Clearly, statistical mechanics, usually employed in systems with very large number of particles, would seemingly not work for such finite systems as the nuclei, neither do other theories which are applicable to condensed matter. The richness of nuclear physics stems from these restrictions. New theories and models are presently being developed. Theories of the structure and reactions of neutron-rich and proton-rich nuclei, called exotic nuclei, halo nuclei, or Borromean nuclei, deal with the wealth of experimental data that became available in the last 35 years. Furthermore, nuclear astrophysics and stellar and Big Bang nucleosynthesis have become a more mature subject. Due to limited space, this review only covers a few selected topics, mainly those with which the authors have worked on. Our aimed potential readers of this review are nuclear physicists and physicists in other areas, as well as graduate students interested in pursuing a career in nuclear physics.

Last results of DIRAC experiment on study hadronic hydrogen-like atoms at PS CERN

NASA Astrophysics Data System (ADS)

Afanasyev, Leonid

2016-04-01

Results on study the hydrogen-like atoms consisting of charged pions and Kaons are presented. The first measurement of K+ π and Kπ+ atoms lifetime was fulfilled basing on identification of 178 ± 49 Kπ pairs from the atom breakup. The measured lifetime is τ = (2.5-1.8+3.0) fs. This value is dictated by properties of the strong πK-interaction at low energy, namely S-wave πK scattering length. The first experimental value of the isospin-odd combination of S-wave πK scattering length was obtained | a0- | =1/3 |a/2 -a3/2 | = (0.11-0.04+0.09) Mπ-1 (ai for isospin I). A dedicated experiment with π+ π atoms allows further study of these already observed atoms. The preliminary results on observation of the long-lived (metastable) states of π+ π atoms are presented. The observation of long-lived states opens the possibility to measure the energy difference between ns and np states - the Lamb shift.

Theory of long-range interactions for Rydberg states attached to hyperfine-split cores

NASA Astrophysics Data System (ADS)

Robicheaux, F.; Booth, D. W.; Saffman, M.

2018-02-01

The theory is developed for one- and two-atom interactions when the atom has a Rydberg electron attached to a hyperfine-split core state. This situation is relevant for some of the rare-earth and alkaline-earth atoms that have been proposed for experiments on Rydberg-Rydberg interactions. For the rare-earth atoms, the core electrons can have a very substantial total angular momentum J and a nonzero nuclear spin I . In the alkaline-earth atoms there is a single (s ) core electron whose spin can couple to a nonzero nuclear spin for odd isotopes. The resulting hyperfine splitting of the core state can lead to substantial mixing between the Rydberg series attached to different thresholds. Compared to the unperturbed Rydberg series of the alkali-metal atoms, the series perturbations and near degeneracies from the different parity states could lead to qualitatively different behavior for single-atom Rydberg properties (polarizability, Zeeman mixing and splitting, etc.) as well as Rydberg-Rydberg interactions (C5 and C6 matrices).

New Cooperative Mechanisms of Low-Energy Nuclear Reactions Using Super Low-Energy External Field

NASA Astrophysics Data System (ADS)

Gareev, F. A.; Zhidkova, I. E.

We propose a new mechanism of LENR: cooperative processes in the whole system, nuclei + atoms + condensed matter, can occur at a smaller threshold energies than the corresponding ones on free constituents. The cooperative processes can be induced and enhanced by low-energy external fields. The excess heat is the emission of internal energy and transmutations at LENR are the result of redistribution of inner energy of the whole system.

Deuteron-induced nucleon transfer reactions within an ab initio framework: First application to p -shell nuclei

DOE PAGES

Raimondi, Francesco; Hupin, Guillaume; Navratil, Petr; ...

2016-05-10

Low-energy transfer reactions in which a proton is stripped from a deuteron projectile and dropped into a target play a crucial role in the formation of nuclei in both primordial and stellar nucleosynthesis, as well as in the study of exotic nuclei using radioactive beam facilities and inverse kinematics. Here, ab initio approaches have been successfully applied to describe the 3H(d,n) 4He and 3He(d,p) 4He fusion processes. An ab initio treatment of transfer reactions would also be desirable for heavier targets. In this work, we extend the ab initio description of (d,p) reactions to processes with light p-shell nuclei. Asmore » a first application, we study the elastic scattering of deuterium on 7Li and the 7Li(d,p) 8Li transfer reaction based on a two-body Hamiltonian. We use the no-core shell model to compute the wave functions of the nuclei involved in the reaction, and describe the dynamics between targets and projectiles with the help of microscopic-cluster states in the spirit of the resonating group method. The shapes of the excitation functions for deuterons impinging on 7Li are qualitatively reproduced up to the deuteron breakup energy. The interplay between d– 7Li and p– 8Li particle-decay channels determines some features of the 9Be spectrum above the d+ 7Li threshold. Our prediction for the parity of the 17.298 MeV resonance is at odds with the experimental assignment. Deuteron stripping reactions with p-shell targets can now be computed ab initio, but calculations are very demanding. Finally, a quantitative description of the 7Li(d,p) 8Li reaction will require further work to include the effect of three-nucleon forces and additional decay channels and to improve the convergence rate of our calculations.« less

Deuteron-induced nucleon transfer reactions within an ab initio framework: First application to p -shell nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raimondi, Francesco; Hupin, Guillaume; Navratil, Petr

Low-energy transfer reactions in which a proton is stripped from a deuteron projectile and dropped into a target play a crucial role in the formation of nuclei in both primordial and stellar nucleosynthesis, as well as in the study of exotic nuclei using radioactive beam facilities and inverse kinematics. Here, ab initio approaches have been successfully applied to describe the 3H(d,n) 4He and 3He(d,p) 4He fusion processes. An ab initio treatment of transfer reactions would also be desirable for heavier targets. In this work, we extend the ab initio description of (d,p) reactions to processes with light p-shell nuclei. Asmore » a first application, we study the elastic scattering of deuterium on 7Li and the 7Li(d,p) 8Li transfer reaction based on a two-body Hamiltonian. We use the no-core shell model to compute the wave functions of the nuclei involved in the reaction, and describe the dynamics between targets and projectiles with the help of microscopic-cluster states in the spirit of the resonating group method. The shapes of the excitation functions for deuterons impinging on 7Li are qualitatively reproduced up to the deuteron breakup energy. The interplay between d– 7Li and p– 8Li particle-decay channels determines some features of the 9Be spectrum above the d+ 7Li threshold. Our prediction for the parity of the 17.298 MeV resonance is at odds with the experimental assignment. Deuteron stripping reactions with p-shell targets can now be computed ab initio, but calculations are very demanding. Finally, a quantitative description of the 7Li(d,p) 8Li reaction will require further work to include the effect of three-nucleon forces and additional decay channels and to improve the convergence rate of our calculations.« less

Theoretical study of triaxial shapes of neutron-rich Mo and Ru nuclei

DOE PAGES

Zhang, C. L.; Bhat, G. H.; Nazarewicz, W.; ...

2015-09-10

Here, whether atomic nuclei can possess triaxial shapes at their ground states is still a subject of ongoing debate. According to theory, good prospects for low-spin triaxiality are in the neutron-rich Mo-Ru region. Recently, transition quadrupole moments in rotational bands of even-mass neutron-rich isotopes of molybdenum and ruthenium nuclei have been measured. The new data have provided a challenge for theoretical descriptions invoking stable triaxial deformations. The purpose of this study is to understand experimental data on rotational bands in the neutron-rich Mo-Ru region, we carried out theoretical analysis of moments of inertia, shapes, and transition quadrupole moments of neutron-richmore » even-even nuclei around 110Ru using self-consistent mean-field and shell model techniques. Methods: To describe yrast structures in Mo and Ru isotopes, we use nuclear density functional theory (DFT) with the optimized energy density functional UNEDF0. We also apply triaxial projected shell model (TPSM) to describe yrast and positive-parity, near-yrast band structures. As a result, our self-consistent DFT calculations predict triaxial ground-state deformations in 106,108Mo and 108,110,112Ru and reproduce the observed low-frequency behavior of moments of inertia. As the rotational frequency increases, a negative-gamma structure, associated with the aligned ν(h 11/2) 2 pair, becomes energetically favored. The computed transition quadrupole moments vary with angular momentum, which reflects deformation changes with rotation; those variations are consistent with experiment. The TPSM calculations explain the observed band structures assuming stable triaxial shapes. Lastly, the structure of neutron-rich even-even nuclei around Ru-110 is consistent with triaxial shape deformations. Our DFT and TPSM frameworks provide a consistent and complementary description of experimental data.« less

Neutron-antineutron oscillations in nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dover, C.B.; Gal, A.; Richard, J.M.

1983-03-01

We present calculations of the neutron-antineutron (n-n-bar) annihilation lifetime T in deuterium, /sup 16/O, and /sup 56/Fe in terms of the free-space oscillation time tau/sub n/n-bar. The coupled Schroedinger equations for the n and n-bar wave functions in a nucleus are solved numerically, using a realistic shell-model potential which fits the empirical binding energies of the neu- p tron orbits, and a complex n-bar-nucleus optical potential obtained from fits to p-bar-atom level shifts. Most previous estimates of T in nuclei, which exhibit large variations, are found to be quite inaccurate. When the nuclear-physics aspects of the problem are handled properlymore » (in particular, the finite neutron binding, the nuclear radius, and the surface diffuseness), the results are found to be rather stable with respect to allowable changes in the parameters of the nuclear model. We conclude that experimental limits on T in nuclei can be used to give reasonably precise constraints on tau/sub n/n-bar: T>10/sup 30/ or 10/sup 31/ yr leads to tau/sub n/n-bar>(1.5--2) x 10/sup 7/ or (5--6) x 10/sup 7/ sec, respectively.« less

Fundamental Studies of Crystal Growth of Microporous Materials

NASA Technical Reports Server (NTRS)

Singh, Ramsharan; Doolittle, John, Jr.; Payra, Pramatha; Dutta, Prabir K.; George, Michael A.; Ramachandran, Narayanan; Schoeman, Brian J.

2003-01-01

Microporous materials are framework structures with well-defined porosity, often of molecular dimensions. Zeolites contain aluminum and silicon atoms in their framework and are the most extensively studied amongst all microporous materials. Framework structures with P, Ga, Fe, Co, Zn, B, Ti and a host of other elements have also been made. Typical synthesis of microporous materials involve mixing the framework elements (or compounds, thereof) in a basic solution, followed by aging in some cases and then heating at elevated temperatures. This process is termed hydrothermal synthesis, and involves complex chemical and physical changes. Because of a limited understanding of this process, most synthesis advancements happen by a trial and error approach. There is considerable interest in understanding the synthesis process at a molecular level with the expectation that eventually new framework structures will be built by design. The basic issues in the microporous materials crystallization process include: (a) Nature of the molecular units responsible for the crystal nuclei formation; (b) Nature of the nuclei and nucleation process; (c) Growth process of the nuclei into crystal; (d) Morphological control and size of the resulting crystal; (e) Surface structure of the resulting crystals; and (f) Transformation of frameworks into other frameworks or condensed structures.

Frequency Dependence of Electron Spin-lattice Relaxation for Semiquinones in Alcohol Solutions

PubMed Central

Elajaili, Hanan B.; Biller, Joshua R.; Eaton, Sandra S.; Eaton, Gareth R.

2014-01-01

The spin-lattice relaxation rates at 293 K for three anionic semiquinones (2,5-di-t-butyl-1,4-benzosemiquinone, 2,6-di-t-butyl-1,4-benzosemiquinone, and 2,3,5,6-tetramethoxy-1,4-benzosemiquinone) were studied at up to 8 frequencies between 250 MHz and 34 GHz in ethanol or methanol solution containing high concentrations of OH-. The relaxation rates are about a factor of 2 faster at lower frequencies than at 9 or 34 GHz. However, in perdeuterated alcohols the relaxation rates exhibit little frequency dependence, which demonstrates that the dominant frequency-dependent contribution to relaxation is modulation of dipolar interactions with solvent nuclei. The relaxation rates were modeled as the sum of two frequency-independent contributions (spin rotation and a local mode) and two frequency-dependent contributions (modulation of dipolar interaction with solvent nuclei and a much smaller contribution from modulation of g anisotropy). The correlation time for modulation of the interaction with solvent nuclei is longer than the tumbling correlation time of the semiquinone and is consistent with hydrogen bonding of the alcohol to the oxygen atoms of the semiquinones. PMID:25261741

The physics of spin polarized gases

NASA Astrophysics Data System (ADS)

Cates, Gordon D.

1995-01-01

Most of our research was connected either directly or indirectly to the study of spin polarized atoms and nuclei, and their applications. In most cases we used lasers to optically pump, and hence polarize, alkali-metal vapors. Spin-exchange collisions were used to transfer the angular momentum to other systems. Of particular interest was our continuing study of the polarization of noble gas nuclei, which are characterized by extremely long spin relaxation times of minutes to many days. During this past research period we have demonstrated several applications of polarized noble gas nuclei that may have important implications for such diverse areas as nondestructive testing and medical diagnostics, as well as many areas in fundamental research. Of particular note is the use of spin-exchange polarized He-3 and Xe-129 for magnetic resonance imaging. At present, our imaging work has focused on the lungs of small animals such as mice and guinea pigs. We believe, however, that our technique would also be useful for nondestructive testing. We have also continued our study of Xe that is polarized in the gaseous state, and subsequently frozen. This novel technique for producing a highly polarized solid has received considerable attention in the NMR community.

High-order above-threshold dissociation of molecules.

PubMed

Lu, Peifen; Wang, Junping; Li, Hui; Lin, Kang; Gong, Xiaochun; Song, Qiying; Ji, Qinying; Zhang, Wenbin; Ma, Junyang; Li, Hanxiao; Zeng, Heping; He, Feng; Wu, Jian

2018-02-27

Electrons bound to atoms or molecules can simultaneously absorb multiple photons via the above-threshold ionization featured with discrete peaks in the photoelectron spectrum on account of the quantized nature of the light energy. Analogously, the above-threshold dissociation of molecules has been proposed to address the multiple-photon energy deposition in the nuclei of molecules. In this case, nuclear energy spectra consisting of photon-energy spaced peaks exceeding the binding energy of the molecular bond are predicted. Although the observation of such phenomena is difficult, this scenario is nevertheless logical and is based on the fundamental laws. Here, we report conclusive experimental observation of high-order above-threshold dissociation of H 2 in strong laser fields where the tunneling-ionized electron transfers the absorbed multiphoton energy, which is above the ionization threshold to the nuclei via the field-driven inelastic rescattering. Our results provide an unambiguous evidence that the electron and nuclei of a molecule as a whole absorb multiple photons, and thus above-threshold ionization and above-threshold dissociation must appear simultaneously, which is the cornerstone of the nowadays strong-field molecular physics. Copyright © 2018 the Author(s). Published by PNAS.

Density-functional theory study of the geometries, stabilities, and electronic properties of Au n Rb (n = 1-10) clusters: comparison with pure gold clusters

NASA Astrophysics Data System (ADS)

Hu, Yan-Fei; Jiang, Gang; Meng, Da-Qiao

2012-01-01

The density functional method with the relativistic effective core potential has been employed to investigate systematically the geometric structures, relative stabilities, growth-pattern behavior, and electronic properties of small bimetallic Au n Rb (n = 1-10) and pure gold Au n (n ≤ 11) clusters. For the geometric structures of the Au n Rb (n = 1-10) clusters, the dominant growth pattern is for a Rb-substituted Au n +1 cluster or one Au atom capped on a Au n -1Rb cluster, and the turnover point from a two-dimensional to a three-dimensional structure occurs at n = 4. Moreover, the stability of the ground-state structures of these clusters has been examined via an analysis of the average atomic binding energies, fragmentation energies, and the second-order difference of energies as a function of cluster size. The results exhibit a pronounced even-odd alternation phenomenon. The same pronounced even-odd alternations are found for the HOMO-LUMO gap, VIPs, VEAs, and the chemical hardness. In addition, about one electron charge transfers from the Au n host to the Rb atom in each corresponding Au n Rb cluster.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marchenko, A. V.; Terukov, E. I.; Egorova, A. Yu.

Impurity iron atoms in vitreous arsenic-selenide As{sub 2}Se{sub 3} films modified by iron form one-electron donor centers with an ionization energy of 0.24 (3) eV (the energy is counted from the conduction-band bottom). The Fermi level is shifted with an increase in the iron concentration from the mid-gap to the donorlevel position of iron due to the filling of one-electron states of the acceptor type lying below the Fermi level. At an iron concentration of ≥3 at %, the electron-exchange process is observed between neutral and ionized iron centers resulting in a change both in the electron density and inmore » the tensor of the electric-field gradient at iron-atom nuclei with increasing temperature above 350 K.« less

Electron shakeoff following the β+ decay of +19Ne and +35Ar trapped ions

NASA Astrophysics Data System (ADS)

Fabian, X.; Fléchard, X.; Pons, B.; Liénard, E.; Ban, G.; Breitenfeldt, M.; Couratin, C.; Delahaye, P.; Durand, D.; Finlay, P.; Guillon, B.; Lemière, Y.; Mauger, F.; Méry, A.; Naviliat-Cuncic, O.; Porobic, T.; Quéméner, G.; Severijns, N.; Thomas, J.-C.

2018-02-01

The electron shakeoff of 19F and 35Cl atoms resulting from the β+ decay of +19Ne and +35Ar ions has been investigated using a Paul trap coupled to a time of flight recoil-ion spectrometer. The charge-state distributions of the recoiling daughter nuclei were compared to theoretical calculations based on the sudden approximation and accounting for subsequent Auger processes. The excellent agreement obtained for 35Cl is not reproduced in 19F. The shortcoming is attributed to the inaccuracy of the independent particle model employed to calculate the primary shakeoff probabilities in systems with rather low atomic numbers. This calls for more elaborate calculations, including explicitly the electron-electron correlations.

The use of neutron scattering to determine the functional structure of glycoside hydrolase.

PubMed

Nakamura, Akihiko; Ishida, Takuya; Samejima, Masahiro; Igarashi, Kiyohiko

2016-10-01

Neutron diffraction provides different information from X-ray diffraction, because neutrons are scattered by atomic nuclei, whereas X-rays are scattered by electrons. One of the key advantages of neutron crystallography is the ability to visualize hydrogen and deuterium atoms, making it possible to observe the protonation state of amino acid residues, hydrogen bonds, networks of water molecules and proton relay pathways in enzymes. But, because of technical difficulties, less than 100 enzyme structures have been evaluated by neutron crystallography to date. In this review, we discuss the advantages and disadvantages of neutron crystallography as a tool to investigate the functional structure of glycoside hydrolases, with some examples. Copyright © 2016 Elsevier Ltd. All rights reserved.

Measurements of Reaction Cross Sections for 9-11C

NASA Astrophysics Data System (ADS)

Nishizuka, Kenji; Takechi, Maya; Ohtsubo, Takashi; Nishimura, Daiki; Fukuda, Mitsunori; Aoki, Kazuya; Abe, Keijiro; Ikeda, Ayaka; Izumikawa, Takuji; Oikawa, Hiroyuki; Ohnishi, Kosuke; Ohno, Junichi; Ohmika, Shunichiro; Kato, Ikuma; Kanke, Yuki; Kanbe, Shunsuke; Kanda, Naoto; Kikuchi, Haruka; Kitagawa, Atsushi; Sato, Shinji; Sayama, Umito; Shimaya, Jiro; Sugihara, Takanobu; Suzuki, Shinji; Suzuki, Takeshi; Takahashi, Hiroki; Taguchi, Yoshisada; Takei, Yuki; Takeuchi, Yuki; Takenouchi, Arashi; Takemoto, Takanori; Tadano, Natsuki; Tanaka, Masaomi; Tanaka, Yutaro; Chikaato, Kazuya; Du, Hang; Nagai, Takumi; Nagumo, Junya; Fukuda, Shigekazu; Hori, Kensyu; Honma, Akira; Machida, Masahiro; Matsunaga, Satoshi; Mizukami, Atsushi; Mihara, Mototsugu; Miyata, Eri; Murooka, Daiki; Yagi, Shoichi; Yamaoka, Shintaro; Yamaguchi, Takayuki; Yokoyama, Kouhei

In order to probe the differences of matter and charge radii of atomic nucleus in the proton-rich C isotopes, measurements of reaction cross sections (σR) for 9-11C on proton targets in the energy range from 50 to 120A MeV were performed at HIMAC facility, NIRS. Owing to the large differences between proton-proton and proton-neutron scattering cross sections at this intermediate energy region, σR data for atomic nuclei on proton targets are expected to have the sensitivity to the differences between proton and neutron distributions in the nucleus. Present preliminary data are compared with the Glauber calculation, which suggest the larger enhancements of proton distributions in 9C and 10C compared to 11C.

The strong Bell inequalities: A proposed experimental test

NASA Technical Reports Server (NTRS)

Fry, Edward S.

1994-01-01

All previous experimental tests of Bell inequalities have required additional assumptions. The strong Bell inequalities (i.e. those requiring no additional assumptions) have never been tested. An experiment has been designed that can, for the first time, provide a definitive test of the strong Bell inequalities. Not only will the detector efficiency loophole be closed; but the locality condition will also be rigorously enforced. The experiment involves producing two Hg-199 atoms by a resonant Raman dissociation of a mercury dimer ((199)Hg2) that is in an electronic and nuclear spin singlet state. Bell inequalities can be tested by measuring angular momentum correlations between the spin one-half nuclei of the two Hg-199 atoms. The method used to make these latter measurements will be described.

Search for variation of fundamental constants and violations of fundamental symmetries using isotope comparisons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berengut, J. C.; Flambaum, V. V.; Kava, E. M.

2011-10-15

Atomic microwave clocks based on hyperfine transitions, such as the caesium standard, tick with a frequency that is proportional to the magnetic moment of the nucleus. This magnetic moment varies strongly between isotopes of the same atom, while all atomic electron parameters remain the same. Therefore the comparison of two microwave clocks based on different isotopes of the same atom can be used to constrain variation of fundamental constants. In this paper, we calculate the neutron and proton contributions to the nuclear magnetic moments, as well as their sensitivity to any potential quark-mass variation, in a number of isotopes ofmore » experimental interest including {sup 201,199}Hg and {sup 87,85}Rb, where experiments are underway. We also include a brief treatment of the dependence of the hyperfine transitions to variation in nuclear radius, which in turn is proportional to any change in quark mass. Our calculations of expectation values of proton and neutron spin in nuclei are also needed to interpret measurements of violations of fundamental symmetries.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thayer, K.J.

The past year has seen several of the Physics Division`s new research projects reach major milestones with first successful experiments and results: the atomic physics station in the Basic Energy Sciences Research Center at the Argonne Advanced Photon Source was used in first high-energy, high-brilliance x-ray studies in atomic and molecular physics; the Short Orbit Spectrometer in Hall C at the Thomas Jefferson National Accelerator (TJNAF) Facility that the Argonne medium energy nuclear physics group was responsible for, was used extensively in the first round of experiments at TJNAF; at ATLAS, several new beams of radioactive isotopes were developed andmore » used in studies of nuclear physics and nuclear astrophysics; the new ECR ion source at ATLAS was completed and first commissioning tests indicate excellent performance characteristics; Quantum Monte Carlo calculations of mass-8 nuclei were performed for the first time with realistic nucleon-nucleon interactions using state-of-the-art computers, including Argonne`s massively parallel IBM SP. At the same time other future projects are well under way: preparations for the move of Gammasphere to ATLAS in September 1997 have progressed as planned. These new efforts are imbedded in, or flowing from, the vibrant ongoing research program described in some detail in this report: nuclear structure and reactions with heavy ions; measurements of reactions of astrophysical interest; studies of nucleon and sub-nucleon structures using leptonic probes at intermediate and high energies; atomic and molecular structure with high-energy x-rays. The experimental efforts are being complemented with efforts in theory, from QCD to nucleon-meson systems to structure and reactions of nuclei. Finally, the operation of ATLAS as a national users facility has achieved a new milestone, with 5,800 hours beam on target for experiments during the past fiscal year.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gurgi, L. A.; Regan, P. H.; Söderström, P. -A.

In-flight fission of a 345 MeV per nucleon 238U primary beam on a 2 mm thick 9Be target has been used to produce and study the decays of a range of neutron-rich nuclei centred around the doubly mid-shell nucleus 170Dy at the RIBF Facility, RIKEN, Japan. The produced secondary fragments of interest were identified event-by-event using the BigRIPS separator. The fragments were implanted into the WAS3ABI position sensitive silicon active stopper which allowed pixelated correlations between implants and their subsequent β-decay. Discrete γ-ray transitions emitted following decays from either metastable states or excited states populated following beta decay were identifiedmore » using the 84 coaxial high-purity germanium (HPGe) detectors of the EURICA spectrometer, which was complemented by 18 additional cerium-doped lanthanum bromide (LaBr3) fast-timing scintillation detectors from the FATIMA collaboration. This paper presents the internal decay of a metastable isomeric excited state in the odd-odd nucleus 168Tb, which corresponds to a single proton-neutron hole configuration in the valence maximum nucleus 170Dy. These data represent the first information on excited states in this nucleus, which is the most neutron-rich odd-odd isotope of terbium (Z=65) studied to date. Nilsson configurations associated with an axially symmetric, prolate-deformed nucleus are proposed for the 168Tb ground state the observed isomeric state by comparison with Blocked BCS-Nilsson calculations.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gurgi, L. A.; Regan, P. H.; Söderström, P. -A.

In-flight fission of a 345 MeV per nucleon 238U primary beam on a 2 mm thick 9Be target has been used to produce and study the decays of a range of neutron-rich nuclei centred around the doubly mid-shell nucleus 170Dy at the RIBF Facility, RIKEN, Japan. The produced secondary fragments of interest were identified event-by-event using the BigRIPS separator. The fragments were implanted into the WAS3ABI position sensitive silicon active stopper which allowed pixelated correlations between implants and their subsequent β-decay. Discrete γ-ray transitions emitted following decays from either metastable states or excited states populated following beta decay were identifiedmore » using the 84 coaxial high-purity germanium (HPGe) detectors of the EURICA spectrometer, which was complemented by 18 additional cerium-doped lanthanum bromide (LaBr 3) fast-timing scintillation detectors from the FATIMA collaboration. This paper presents the internal decay of a metastable isomeric excited state in the odd-odd nucleus 168Tb, which corresponds to a single proton-neutron hole configuration in the valence maximum nucleus 170Dy. These data represent the first information on excited states in this nucleus, which is the most neutron-rich odd-odd isotope of terbium (Z = 65) studied to date. Here, Nilsson configurations associated with an axially symmetric, prolate-deformed nucleus are proposed for the 168Tb ground state the observed isomeric state by comparison with Blocked BCS-Nilsson calculations.« less

Laboratory search for a long-range T-odd, P-odd interaction from axionlike particles using dual-species nuclear magnetic resonance with polarized 129Xe and 131Xe gas.

PubMed

Bulatowicz, M; Griffith, R; Larsen, M; Mirijanian, J; Fu, C B; Smith, E; Snow, W M; Yan, H; Walker, T G

2013-09-06

Various theories beyond the standard model predict new particles with masses in the sub-eV range with very weak couplings to ordinary matter. A new P-odd and T-odd interaction between polarized and unpolarized nucleons proportional to K·r is one such possibility, where r is the distance between the nucleons and K is the spin of the polarized nucleon. Such an interaction involving a scalar coupling gs at one vertex and a pseudoscalar coupling gp at the polarized nucleon vertex can be induced by the exchange of spin-0 bosons. We used the NMR cell test station at Northrop Grumman Corporation to search for NMR frequency shifts in polarized 129Xe and 131Xe when a nonmagnetic zirconia rod is moved near the NMR cell. Long (T2∼20  s) spin-relaxation times allow precision measurements of the NMR frequency ratios, which are insensitive to magnetic field fluctuations. Combined with existing theoretical calculations of the neutron spin contribution to the nuclear angular momentum in xenon nuclei, the measurements improve the laboratory upper bound on the product gsgp(n) by 2 orders of magnitude for distances near 1 mm. The sensitivity of this technique can be increased by at least two more orders of magnitude.

Heavy Metal Stars

NASA Astrophysics Data System (ADS)

2001-08-01

La Silla Telescope Detects Lots of Lead in Three Distant Binaries Summary Very high abundances of the heavy element Lead have been discovered in three distant stars in the Milky Way Galaxy . This finding strongly supports the long-held view that roughly half of the stable elements heavier than Iron are produced in common stars during a phase towards the end of their life when they burn their Helium - the other half results from supernova explosions. All the Lead contained in each of the three stars weighs about as much as our Moon. The observations show that these "Lead stars" - all members of binary stellar systems - have been more enriched with Lead than with any other chemical element heavier than Iron. This new result is in excellent agreement with predictions by current stellar models about the build-up of heavy elements in stellar interiors. The new observations are reported by a team of Belgian and French astronomers [1] who used the Coude Echelle Spectrometer on the ESO 3.6-m telescope at the La Silla Observatory (Chile). PR Photo 26a/01 : A photo of HD 196944 , one of the "Lead stars". PR Photo 26b/01 : A CES spectrum of HD 196944 . The build-up of heavy elements Astronomers and physicists denote the build-up of heavier elements from lighter ones as " nucleosynthesis ". Only the very lightest elements (Hydrogen, Helium and Lithium [2]) were created at the time of the Big Bang and therefore present in the early universe. All the other heavier elements we now see around us were produced at a later time by nucleosynthesis inside stars. In those "element factories", nuclei of the lighter elements are smashed together whereby they become the nuclei of heavier ones - this process is known as nuclear fusion . In our Sun and similar stars, Hydrogen is being fused into Helium. At some stage, Helium is fused into Carbon, then Oxygen, etc. The fusion process requires positively charged nuclei to move very close to each other before they can unite. But with increasing atomic mass and hence, increasing positive charge of the nuclei, the electric repulsion between the nuclei becomes stronger and stronger. In fact, the fusion process only works up to a certain mass limit, corresponding to the element Iron [2]. All elements that are heavier than Iron cannot be produced via this path. But then, how were those heavy elements we now find on the Earth produced in the first place? From where comes the Zirconium in artificial diamonds, the Barium that colours fireworks, the Tungsten in the filaments in electric bulbs? Which process made the Lead in your car battery? Beyond iron The production of elements heavier than Iron takes place by adding neutrons to the atomic nuclei . These neutral particles do not feel any electrical repulsion from the charged nuclei. They can therefore easily approach them and thereby create heavier nuclei. This is indeed the way the heaviest chemical elements are built up. There are actually two different stellar environments where this process of "neutron capture" can happen. One place where this process occurs is inside very massive stars when they explode as supernovae . In such a dramatic event, the build-up proceeds very rapidly, via the so-called "r-process" ( "r" for rapid ). The AGB stars But not all heavy elements are created in such an explosive way. A second possibility follows a more "peaceful" road. It takes place in rather normal stars, when they burn their Helium towards the end of their lives. In the so-called "s-process" ( "s" for slow ), heavier elements are then produced by a rather gentle addition of neutral neutrons to atomic nuclei. In fact, roughly half of all the elements heavier than Iron are believed to be synthesized by this process during the late evolutionary phases of stars. This process takes place during a specific stage of stellar evolution, known as the "AGB" phase [3]. It occurs just before an old star expels its gaseous envelope into the surrounding interstellar space and sometime thereafter dies as a burnt-out, dim "white dwarf" . Stars with masses between 0.8 and 8 times that of the Sun are believed to evolve to AGB-stars and to end their lives in this particular way. At the same time, they produce beautiful nebulae like the "Dumbbell Nebula". Our Sun will also end its active life this way, probably some 7 billion years from now. Low-metallicity stars The detailed understanding of the "s-process" and, in particular, where it takes place inside an AGB-star, has been an area of active research for many years. Current state-of-the-art computer-based stellar models predict that the s-process should be particularly efficient in stars with a comparatively low content of metals ("metal-poor" or "low-metallicity" stars) . In such stars - which were born at an early epoch in our Galaxy and are therefore quite old - the "s-process" is expected to effectively produce atomic nuclei all the way up to the most heavy, stable ones, like Lead (atomic number 82 [2]) and Bismuth (atomic number 83) - since more neutrons are available per Iron-seed nucleus when there are fewer such nuclei (as compared to the solar composition). Once these elements have been produced, the addition of more s-process neutrons to those nuclei will only produce unstable elements that decay back to Lead. Hence, when the s-process is sufficiently efficient, atomic nuclei with atomic numbers around 82, that is, the Lead region, just continue to pile up. As a result, when compared to stars with "normal" abundances of the metals (like our Sun), those low-metallicity stars should thus exhibit a significant "over-abundance" of those very heavy elements with respect to Iron, in particular of Lead . Looking for Lead Direct observational support for this theoretical prediction would be the discovery of some low-metallicity stars with a high abundance of Lead. At the same time, the measured amounts of all the heavy elements and their relative abundances would provide very valuable information and strongly reinforce our current understanding of heavy element nucleosynthesis. But detecting the element Lead is not easy - the expected spectral lines of Lead in stellar spectra are relatively weak, and they are blended with many nearby absorption lines of other elements. Moreover, bona-fide, low-metallicity AGB stars appear to be extremely rare in the solar neighborhood . But if the necessary observations are so difficult, how is it then possible to probe nucleosynthesis in low-metallicity AGB stars? CH-stars in binary systems ESO PR Photo 26a/01 ESO PR Photo 26a/01 [Preview - JPEG: 350 x 400 pix - 232k] [Normal - JPEG: 700 x 800 pix - 616k] Caption : One of the three Lead stars, HD 196944 that was analyzed in the present research programme (at the center of the field). This star lies about 1600 light years away in the constellation Aquarius. At magnitude 9, it is not visible to the unaided eye, but easily seen through a small amateur telescope. Still, the detailed spectroscopic study reported in this Press release that revealed a high abundance of Lead in this star required a 4-m class telescope. This DSS-image are copyright by the UK SERC/PPARC (Particle Physics and Astronomy Research Council, formerly Science and Engineering Research Council), the Anglo-Australian Telescope Board and the Association of Universities for Research in Astronomy (AURA). The spikes seen in this photo are an optical effect in the telescope. In a determined effort in this direction, a team of Belgian and French astronomers [1] decided to try to detect the presence of Lead in some "CH-stars" [4] that are located about 1600 light-years away, high above the main plane of our Milky Way Galaxy. Over-abundance of some heavy elements has been observed in some "CH-stars". But CH-stars are not very luminous and have not yet evolved to the AGB phase. Hence they are totally unable to produce heavy elements. So how can there be heavy elements in the CH-stars? This mystery was solved when it was realized that the CH-stars all belong to binary systems and that they therefore have a companion star [5]. That companion is now a white dwarf star and was therefore at some earlier moment an AGB star ! During its AGB-phase, the companion star expelled much of its material, eventually producing the "planetary nebula" phenomenon, referred to above. In this process, a lot of its material, enriched with heavy elements produced by the "s-process" during the AGB phase, was deposited in the atmosphere of the CH-star that is now observed. The former AGB-star, now a slowly cooling, dim white-dwarf star, still orbits the CH-star. For this reason, the atmospheric composition of a CH-star actually carries the signature of the nucleosynthesis that took place deep inside the companion AGB star at an earlier epoch. Spectroscopic observations of CH-stars thus provide the opportunity to probe the predicted s-process in low-metallicity stars. Three stars with Lead ESO PR Photo 26b/01 ESO PR Photo 26b/01 [Preview - JPEG: 400 x 371 pix - 95k] [Normal - JPEG: 800 x 741 pix - 240k] Caption : A high-resolution spectrum of the CH-star HD 196944, obtained with the CES instrument on the ESO 3.6-m telescope in September 2000. The observed spectrum (dots) shows many absorption lines from elements that are usually seen in stars. The red line shows a model in which elements (in particular those produced by the s-process) are present in normal quantities, compared to Iron. The blue line instead shows a model where s-processing has occured. It is obvious that the red line does not fit, only the blue line reproduces the observed absorption line at wavelength 405.781 nm caused by Lead (Pb) atoms in the atmosphere of this star. A subsequent, detailed analysis demonstrated that HD 196944 is a true "Lead star". Technical information about this photo is available below. A necessary condition for these observations to succeed is a very high spectral resolution in order to detect the spectral line of Lead (Pb), in particular to "resolve" it among the many absorption lines from other elements, present in the stellar spectrum in this wavelength region. Moreover, a fairly large telescope is needed as the stars to be observed are relatively rare, hence distant and faint for this kind of demanding observations. The Belgian and French astronomers decided to use the Coude Echelle Spectrometer (CES) at the ESO 3.6-m telescope on La Silla, a telescope/instrument combination offering some hope of success for these difficult observations. Spectra of three southern stars, HD 187861, HD 196944 and HD 224959 , were obtained during two nights in September 2000 and found to be of excellent quality. The scientists were very pleased to find that the Lead absorption line was clearly present and very strong in the spectra of all three stars . A subsequent, detailed analysis demonstrated that the three stars all have a substantial overabundance of Lead. Moreover, from the measured abundances of other elements in these spectra, it is also clear that this Lead has been formed in the s-process . The astronomers were able to prove that the Lead cannot originate from the competing "r-process" that occurs in other environments like supernova explosions. " This is the first detection of a Lead-star ", explains Sophie Van Eck from the Institut d'Astronomie et d'Astrophysique of the Université Libre de Bruxelles (Belgium). " These stars are almost exclusively enriched with Lead. Moreover, the abundances in all three stars show a remarkable similarity ." How does the s-process operate? The high abundance of Lead in these otherwise low-metallicity stars also provides detailed clues on how the s-process operates inside the AGB stars. When a Carbon-13 nucleus (i.e. a nucleus with 6 protons and 7 neutrons [2]) is hit by a Helium-4 nucleus (2 protons and 2 neutrons), they fuse to form Oxygen-16 (8 protons and 8 neutrons). In this process - as can be seen by adding the numbers - one neutron is released. It is exactly these surplus neutrons that become the building-blocks for making heavier elements via the s-process. Hence the true source of the required neutrons is the Carbon-13 isotope, which is in turn produced by fusion of normal carbon (Carbon-12) and protons, i.e. hydrogen nuclei. However, an additional problem is that it seems that nowhere inside the star would there be sufficient Carbon and Hydrogen in the same place to allow this process to take off. Indeed most hydrogen nuclei have already been "used up" and have fused to heavier nuclei, including Carbon. But the observations now prove that the s-process does happen - how is this then possible? Mixing the star Current models of stellar interiors suggest that a moderate, "partial" mixing occurs that occasionally drags Hydrogen down to the Carbon-rich inner regions (and some Carbon moves up into the Hydrogen-rich region). It is still not clearly understood exactly how this process operates, but the Belgian astronomers independently predicted that if such a "partial mixing process" does take place in a low-metallicity star, then Lead-stars should exist and it should also be possible to observe them. " Our discovery of these Lead stars is without any doubt the clearest signature of that model prediction we have today ", states Sophie Van Eck . " The excellent agreement between predicted and observed abundances reinforces our current understanding of the detailed operation of the s-process in the deep interiors of the stars, and thus constitutes an important piece of information on how the heaviest stable elements in the universe are formed ." Three moons and your car battery The astronomers altogether found a mass of Lead in each of the three stars that is about the same as the mass of our Moon (7.4 x 10 22 kg). Stars like these were once the most efficient Lead factories in the Universe. It is likely that the Lead in your car battery was once produced in such a low-metallicity star. From that star, it was later dispersed into the interstellar medium and was present in the cloud of dust and gas from which the Solar System and hence our Earth was formed. More information The research described in this Press Release is reported in a scientific article ("Discovery of three Lead stars" by S. Van Eck, S. Goriely, A. Jorissen and B. Plez) that appears in the August 23, 2001 issue of the science journal "Nature". Notes [1]: The team consists of Sophie Van Eck , Stéphane Goriely , Alain Jorissen (all Institut d'Astronomie et d'Astrophysique de l'Université Libre de Bruxelles, Belgium) and Bertrand Plez (Groupe de Recherche en Astronomie et Astrophysique en Languedoc, Université de Montpellier II - GRAAL), France). Sophie Van Eck was an ESO fellow (1999-2000). [2] The "atomic mass" of a chemical element is the total mass of the positively charged protons and neutral neutrons in the atomic nucleus. The "atomic number" of a chemical element is equal to the number of protons in the nucleus. Different isotopes of a chemical element all have the same number of protons in the nuclei, but a different number of neutrons. For the principal (most abundant) isotopes of the elements mentioned in this text, the "atomic mass" (expressed in "atomic mass units" (amu)) is approximately: Hydrogen : 1 atomic mass unit (with 1 proton in the nucleus); Helium : 4 atomic mass units (2 protons + 2 neutrons); Lithium : 7 atomic mass units (3 protons + 4 neutrons); Carbon : 12 atomic mass units (6 protons + 6 neutrons); Oxygen : 16 atomic mass units (8 protons + 8 neutrons); Iron : 56 atomic mass units (26 protons + 30 neutrons); Zirconium : 90 atomic mass units (40 protons + 50 neutrons); Barium : 138 atomic mass units (56 protons + 82 neutrons); Tungsten : 184 atomic mass units (74 protons + 110 neutrons); Lead : 208 atomic mass units (82 protons + 126 neutrons); Bismuth : 209 atomic mass units (83 protons + 126 neutrons) [3] "AGB" stands for "Asymptotic Giant Branch"; a location in the HR-diagramme (a plot of stellar colours and luminosities) of evolved stars in which hydrogen and helium burning occurs in two concentric shells and elements heavier than iron are produced via the s-process. [4] The "CH-stars" owe their name to the prominent bands of the CH-molecule observed in their spectrum. [5] The fact that CH-stars are all double stars was discovered by the Canadian astronomer Robert McClure in 1984. Technical information about the photos PR Photo 26b/01 shows a small section of the reduced spectrum of the CH-star HD 196944, near wavelength 4050 Angstrom. It was obtained during a 90-min exposure with the Coude Echelle Spectrometer at the ESO 3.6-m telescope on La Silla in 16 September 2000. The spectral resolution is 135 000.

A test for correction made to spin systematics for coupled band in doubly-odd nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Vinod, E-mail: vinod2.k2@gmail.com

2015-12-15

Systematic Spin Assignments were generally made by using the argument that the energy of levels is a function of neutron number. In the present systematics, the excitation energy of the levels incorporated the effect of nuclear deformation and signature splitting. The nuclear deformation changes toward the mid-shell, therefore a smooth variation in the excitation energy of the levels is observed towards the mid-shell, that intended to make systematics as a function of neutron number towards the mid-shell. Another term “signature splitting” that push the energy of levels for odd- and even-spin sequences up and down, caused the different energy variationmore » pattern for odd- and even-spin sequences. The corrections made in the spin systematics were tested for the known spins of various isotopic chain. In addition, the inconsistency in spin assignments made by the spin systematics and other methods of the configuration πh{sub 11/2} ⊗ νh{sub 11/2} band belonging to {sup 112,114,116}Cs, {sup 126}Pr, and {sup 138}Pr, as an example, was resolved by the correctionmade in the present spin systematics.« less

Study of Gamow-Teller strength and associated weak-rates on odd-A nuclei in stellar matter

NASA Astrophysics Data System (ADS)

Majid, Muhammad; Nabi, Jameel-Un; Riaz, Muhammad

In a recent study by Cole et al. [A. L. Cole et al., Phys. Rev. C 86 (2012) 015809], it was concluded that quasi-particle random phase approximation (QRPA) calculations show larger deviations and overestimate the total experimental Gamow-Teller (GT) strength. It was also concluded that QRPA calculated electron capture rates exhibit larger deviation than those derived from the measured GT strength distributions. The main purpose of this study is to probe the findings of the Cole et al. paper. This study gives useful information on the performance of QRPA-based nuclear models. As per simulation results, the capturing of electrons that occur on medium heavy isotopes have a significant role in decreasing the ratio of electron-to-baryon content of the stellar interior during the late stages of core evolution. We report the calculation of allowed charge-changing transitions strength for odd-A fp-shell nuclei (45Sc and 55Mn) by employing the deformed pn-QRPA approach. The computed GT transition strength is compared with previous theoretical calculations and measured data. For stellar applications, the corresponding electron capture rates are computed and compared with rates using previously calculated and measured GT values. Our finding shows that our calculated results are in decent accordance with measured data. At higher stellar temperature, our calculated electron capture rates are larger than those calculated by independent particle model (IPM) and shell model. It was further concluded that at low temperature and high density regions, the positron emission weak-rates from 45Sc and 55Mn may be neglected in simulation codes.

Parameterization of fission barrier heights of medium, heavy and super heavy nuclei

NASA Astrophysics Data System (ADS)

Manjunatha, H. C.

2017-12-01

A new semi empirical formula is proposed for fission barrier heights of medium, heavy and super heavy nuclei in the atomic number region 50 ≤ Z ≤ 130. The fitting parameters for the proposed formula are obtained by making a polynomial fit to the available theoretical and experimental data. The calculated fission barrier heights are compared with that of experiments and other theoretical models such as SHF(SLy6) (Burvenich et al. in Phys Rev C 69:014307, 2004), SHFB(SkM) (Baran et al. in Nucl Phys A 944:442, 2015), FRLDM (Möller et al. in Phys Rev C 79:064304, 2009), ETFSI (SkSC4) with Skyrme SkSC4 force (Mamdouh et al. in Nucl Phys A 679:337, 2001), WS (Kowal et al. in Phys Rev C 82:014303, 2010) and CDFT(DD-ME2) (Abusara et al. in Phys Rev C 85:024314, 2012). The standard deviation for fission barrier heights produced by present formula is evaluated. The good agreement of present formula with the experiments and other models suggests that the present formula could be used to evaluate the fission barrier heights of medium, heavy and super heavy nuclei in the region 50 ≤ Z ≤ 130. This formula is a first of its kind that produces fission barrier heights of 2858 nuclei with the only simple inputs of only neutron number (N), proton number (Z) and mass number (A).

Parameterization of fission barrier heights of medium, heavy and super heavy nuclei

NASA Astrophysics Data System (ADS)

Manjunatha, H. C.

2018-04-01

A new semi empirical formula is proposed for fission barrier heights of medium, heavy and super heavy nuclei in the atomic number region 50 ≤ Z ≤ 130. The fitting parameters for the proposed formula are obtained by making a polynomial fit to the available theoretical and experimental data. The calculated fission barrier heights are compared with that of experiments and other theoretical models such as SHF(SLy6) (Burvenich et al. in Phys Rev C 69:014307, 2004), SHFB(SkM) (Baran et al. in Nucl Phys A 944:442, 2015), FRLDM (Möller et al. in Phys Rev C 79:064304, 2009), ETFSI (SkSC4) with Skyrme SkSC4 force (Mamdouh et al. in Nucl Phys A 679:337, 2001), WS (Kowal et al. in Phys Rev C 82:014303, 2010) and CDFT(DD-ME2) (Abusara et al. in Phys Rev C 85:024314, 2012). The standard deviation for fission barrier heights produced by present formula is evaluated. The good agreement of present formula with the experiments and other models suggests that the present formula could be used to evaluate the fission barrier heights of medium, heavy and super heavy nuclei in the region 50 ≤ Z ≤ 130. This formula is a first of its kind that produces fission barrier heights of 2858 nuclei with the only simple inputs of only neutron number (N), proton number (Z) and mass number (A).

Physical processes in comets

NASA Technical Reports Server (NTRS)

Whipple, F. L.; Huebner, W. F.

1976-01-01

The paper discusses physical processes in comets which involve solar and nuclear radial forces that affect the motions of gases and icy grains, gas-phase chemistry very close to the nuclei of large comets near the sun, sublimation of icy grains, dissociation of parent molecules into radicals and of radicals into atoms, and ionization by sunlight and collisions. The composition and dimensions of nuclei are examined along with variations in intrinsic brightness, the nature of volatiles, gas production rates in the coma, characteristics of icy grains in the coma, and the structure of streamers, ion tails, and dust tails. The structure of the coma is described in detail on the basis of spectroscopic observations of several comets. The origin of comets is briefly reviewed together with the relation of comets to earth, the interplanetary complex, and the interstellar medium. Desirable future observations are noted, especially by space missions to comets.

The tightly bound nuclei in the liquid drop model

NASA Astrophysics Data System (ADS)

Sree Harsha, N. R.

2018-05-01

In this paper, we shall maximise the binding energy per nucleon function in the semi-empirical mass formula of the liquid drop model of the atomic nuclei to analytically prove that the mean binding energy per nucleon curve has local extrema at A ≈ 58.6960, Z ≈ 26.3908 and at A ≈ 62.0178, Z ≈ 27.7506. The Lagrange method of multipliers is used to arrive at these results, while we have let the values of A and Z take continuous fractional values. The shell model that shows why 62Ni is the most tightly bound nucleus is outlined. A brief account on stellar nucleosynthesis is presented to show why 56Fe is more abundant than 62Ni and 58Fe. We believe that the analytical proof presented in this paper can be a useful tool to the instructors to introduce the nucleus with the highest mean binding energy per nucleon.

A method to obtain static potential for electron-molecule scattering

NASA Astrophysics Data System (ADS)

Srivastava, Rajesh; Das, Tapasi; Stauffer, Allan

2014-05-01

Electron scattering from molecules is complicated by the fact that molecules are a multi-centered target with the nuclei of the constituent atoms being a center of charge. One of the most important parts of a scattering calculation is to obtain the static potential which represents the interaction of the incident electron with the unperturbed charge distribution of the molecule. A common way to represent the charge distribution of molecules is with Gaussian orbitals centered on the various nuclei. We have derived a way to calculate spherically-averaged molecular static potentials using this form of molecular wave function which is mostly analytic. This method has been applied to elastic electron scattering from water molecules and we obtained differential cross sections which are compared with previous experimental and theoretical results. The method can be extended to more complex molecules. One of us (RS) is thankful to IAEA, Vienna, Austria and DAE-BRNS, Mumbai, India for financial support.

α decay and cluster radioactivity of nuclei of interest to the synthesis of Z =119 , 120 isotopes

NASA Astrophysics Data System (ADS)

Poenaru, D. N.; Gherghescu, R. A.

2018-04-01

Super-heavy nuclei of interest for the forthcoming synthesis of the isotopes with Z =119 , 120 are investigated. One of the very interesting latest experiments was performed at the velocity filter SHIP (GSI Darmstadt) trying to produce 299120 in a fusion reaction 248Cm(54Cr,3 n )299120 . We report calculations of α -decay half-lives using four models: AKRA (Akrawy), ASAF (analytical superasymmetric fission), UNIV (universal formula), and semFIS (semi-empirical formula based on fission theory). The released energy, Q , is calculated using the theoretical model of atomic masses, WS4. For Sr,9492 cluster radioactivity of 120,302300 we predict a branching ratio relative to α decay of -0.10 and 0.49, respectively, meaning that it is worth trying to detect such kinds of decay modes in competition with α decay.

Visualizing and Steering Dissociative Frustrated Double Ionization of Hydrogen Molecules

NASA Astrophysics Data System (ADS)

Zhang, Wenbin; Yu, Zuqing; Gong, Xiaochun; Wang, Junping; Lu, Peifen; Li, Hui; Song, Qiying; Ji, Qinying; Lin, Kang; Ma, Junyang; Li, Hanxiao; Sun, Fenghao; Qiang, Junjie; Zeng, Heping; He, Feng; Wu, Jian

2017-12-01

We experimentally visualize the dissociative frustrated double ionization of hydrogen molecules by using few-cycle laser pulses in a pump-probe scheme, in which process the tunneling ionized electron is recaptured by one of the outgoing nuclei of the breaking molecule. Three internuclear distances are recognized to enhance the dissociative frustrated double ionization of molecules at different instants after the first ionization step. The recapture of the electron can be further steered to one of the outgoing nuclei as desired by using phase-controlled two-color laser pulses. Both the experimental measurements and numerical simulations suggest that the Rydberg atom is favored to emit to the direction of the maximum of the asymmetric optical field. Our results on the one hand intuitively visualize the dissociative frustrated double ionization of molecules, and on the other hand open the possibility to selectively excite the heavy fragment ejected from a molecule.

Theoretical investigation of gas-surface interactions

NASA Technical Reports Server (NTRS)

Dyall, Kenneth G.

1990-01-01

A Dirac-Hartree-Fock code was developed for polyatomic molecules. The program uses integrals over symmetry-adapted real spherical harmonic Gaussian basis functions generated by a modification of the MOLECULE integrals program. A single Gaussian function is used for the nuclear charge distribution, to ensure proper boundary conditions at the nuclei. The Gaussian primitive functions are chosen to satisfy the kinetic balance condition. However, contracted functions which do not necessarily satisfy this condition may be used. The Fock matrix is constructed in the scalar basis and transformed to a jj-coupled 2-spinor basis before diagonalization. The program was tested against numerical results for atoms with a Gaussian nucleus and diatomic molecules with point nuclei. The energies converge on the numerical values as the basis set size is increased. Full use of molecular symmetry (restricted to D sub 2h and subgroups) is yet to be implemented.

Complexity made simple

NASA Astrophysics Data System (ADS)

2010-02-01

With their passion for analysing the world by breaking it down into ever-smaller pieces, most physicists are "reductionists" at heart. Whether through tradition or instinct, our natural inclination is to reduce matter first to molecules and then to atoms and on to nuclei, nucleons, quarks and beyond. But this approach, while astonishingly successful in terms of understanding the fundamental particles and forces of nature, does not always work. In other words, the whole can often be more than the sum of the parts.

Physics of Spin-Polarized Media

DTIC Science & Technology

2007-11-21

midsection of the cell serving as the cathode, and liquid molten salt outside the cell serving as the anode [5]. This new method is very promising for of...filling atomic clock and magnetometer cells by electrolysis through the glass walls; (6) new investigations of optical pumping and magnetic resonances...cesium vapor can be used to polarize 3 Cs nuclei in CsH salt that coats the walls of a vapor cell. This result, an important first step, has been

Cosmic-ray abundances of the even charge elements from Sn-50 to Ce-58 measured on HEAO-3

NASA Technical Reports Server (NTRS)

Stone, E. C.; Garrard, T. L.; Krombel, K. E.; Binns, W. R.; Israel, M. H.; Klarmann, J.; Brewster, N. R.; Fickle, R. K.; Waddington, C. J.

1983-01-01

Elements with even atomic number (Z) in the interval Z = 50-58 have been resolved in the cosmic radiation using the Heavy Nuclei Experiment on the HEAO-3 satellite. The observation that Sn-50 and Ba-56 are more abundant than Te-52 and Xe-54 indicates a substantial s-process contribution to the cosmic ray source. A significant abundance of Ce-58 provides further support for this finding.

Complete solution of electronic excitation and ionization in electron-hydrogen molecule scattering

DOE PAGES

Zammit, Mark C.; Savage, Jeremy S.; Fursa, Dmitry V.; ...

2016-06-08

The convergent close-coupling method has been used to solve the electron-hydrogen molecule scattering problem in the fixed-nuclei approximation. Excellent agreement with experiment is found for the grand total, elastic, electronic-excitation, and total ionization cross sections from the very low to the very high energies. This shows that for the electronic degrees of freedom the method provides a complete treatment of electron scattering on molecules as it does for atoms.

Neutron production by cosmic-ray muons in various materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manukovsky, K. V.; Ryazhskaya, O. G.; Sobolevsky, N. M.

The results obtained by studying the background of neutrons produced by cosmic-raymuons in underground experimental facilities intended for rare-event searches and in surrounding rock are presented. The types of this rock may include granite, sedimentary rock, gypsum, and rock salt. Neutron production and transfer were simulated using the Geant4 and SHIELD transport codes. These codes were tuned via a comparison of the results of calculations with experimental data—in particular, with data of the Artemovsk research station of the Institute for Nuclear Research (INR, Moscow, Russia)—as well as via an intercomparison of results of calculations with the Geant4 and SHIELD codes.more » It turns out that the atomic-number dependence of the production and yield of neutrons has an irregular character and does not allow a description in terms of a universal function of the atomic number. The parameters of this dependence are different for two groups of nuclei—nuclei consisting of alpha particles and all of the remaining nuclei. Moreover, there are manifest exceptions from a power-law dependence—for example, argon. This may entail important consequences both for the existing underground experimental facilities and for those under construction. Investigation of cosmic-ray-induced neutron production in various materials is of paramount importance for the interpretation of experiments conducted at large depths under the Earth’s surface.« less

The Initial Flow of Classical Gluon Fields in Heavy Ion Collisions

NASA Astrophysics Data System (ADS)

Fries, Rainer J.; Chen, Guangyao

2015-03-01

Using analytic solutions of the Yang-Mills equations we calculate the initial flow of energy of the classical gluon field created in collisions of large nuclei at high energies. We find radial and elliptic flow which follows gradients in the initial energy density, similar to a simple hydrodynamic behavior. In addition we find a rapidity-odd transverse flow field which implies the presence of angular momentum and should lead to directed flow in final particle spectra. We trace those energy flow terms to transverse fields from the non-abelian generalization of Gauss' Law and Ampere's and Faraday's Laws.

Pseudo-majoron as light mediator of singlet scalar dark matter

DOE PAGES

Ma, Ernest; Maniatis, Markos

2017-07-28

In the singlet-triplet majoron model of neutrino mass, lepton number is spontaneously broken. If it is also softly broken, then a naturally light pseudoscalar particle ηI exists. It may then act as a light mediator for a real singlet scalar χ with odd dark parity. It is itself unstable, but decays dominantly to two neutrinos through its triplet scalar component, thereby not disturbing the cosmic microwave background (CMB). It also mixes with the standard-model Higgs boson only in one loop, thereby not contributing significantly to the elastic scattering of χ off nuclei in dark-matter direct-search experiments.

On the Mass of Atoms in Molecules: Beyond the Born-Oppenheimer Approximation

NASA Astrophysics Data System (ADS)

Scherrer, Arne; Agostini, Federica; Sebastiani, Daniel; Gross, E. K. U.; Vuilleumier, Rodolphe

2017-07-01

Describing the dynamics of nuclei in molecules requires a potential energy surface, which is traditionally provided by the Born-Oppenheimer or adiabatic approximation. However, we also need to assign masses to the nuclei. There, the Born-Oppenheimer picture does not account for the inertia of the electrons, and only bare nuclear masses are considered. Nowadays, experimental accuracy challenges the theoretical predictions of rotational and vibrational spectra and requires the participation of electrons in the internal motion of the molecule. More than 80 years after the original work of Born and Oppenheimer, this issue has still not been solved, in general. Here, we present a theoretical and numerical framework to address this problem in a general and rigorous way. Starting from the exact factorization of the electron-nuclear wave function, we include electronic effects beyond the Born-Oppenheimer regime in a perturbative way via position-dependent corrections to the bare nuclear masses. This maintains an adiabaticlike point of view: The nuclear degrees of freedom feel the presence of the electrons via a single potential energy surface, whereas the inertia of electrons is accounted for and the total mass of the system is recovered. This constitutes a general framework for describing the mass acquired by slow degrees of freedom due to the inertia of light, bounded particles; thus, it is applicable not only in electron-nuclear systems but in light-heavy nuclei or ions as well. We illustrate this idea with a model of proton transfer, where the light particle is the proton and the heavy particles are the oxygen atoms to which the proton is bounded. Inclusion of the light-particle inertia allows us to gain orders of magnitude in accuracy. The electron-nuclear perspective is adopted, instead, to calculate position-dependent mass corrections using density functional theory for a few polyatomic molecules at their equilibrium geometry. These data can serve as input for the computation of high-precision molecular spectra.

Practical Applications of Cosmic Ray Science: Spacecraft, Aircraft, Ground-Based Computation and Control Systems, Exploration, and Human Health and Safety

NASA Technical Reports Server (NTRS)

Koontz, Steve

2015-01-01

In this presentation a review of galactic cosmic ray (GCR) effects on microelectronic systems and human health and safety is given. The methods used to evaluate and mitigate unwanted cosmic ray effects in ground-based, atmospheric flight, and space flight environments are also reviewed. However not all GCR effects are undesirable. We will also briefly review how observation and analysis of GCR interactions with planetary atmospheres and surfaces and reveal important compositional and geophysical data on earth and elsewhere. About 1000 GCR particles enter every square meter of Earth’s upper atmosphere every second, roughly the same number striking every square meter of the International Space Station (ISS) and every other low- Earth orbit spacecraft. GCR particles are high energy ionized atomic nuclei (90% protons, 9% alpha particles, 1% heavier nuclei) traveling very close to the speed of light. The GCR particle flux is even higher in interplanetary space because the geomagnetic field provides some limited magnetic shielding. Collisions of GCR particles with atomic nuclei in planetary atmospheres and/or regolith as well as spacecraft materials produce nuclear reactions and energetic/highly penetrating secondary particle showers. Three twentieth century technology developments have driven an ongoing evolution of basic cosmic ray science into a set of practical engineering tools needed to design, test, and verify the safety and reliability of modern complex technological systems and assess effects on human health and safety effects. The key technology developments are: 1) high altitude commercial and military aircraft; 2) manned and unmanned spacecraft; and 3) increasingly complex and sensitive solid state micro-electronics systems. Space and geophysical exploration needs drove the development of the instruments and analytical tools needed to recover compositional and structural data from GCR induced nuclear reactions and secondary particle showers. Finally, the possible role of GCR secondary particle showers in addressing an important homeland security problem, finding nuclear contraband and weapons, will be briefly reviewed.

Precision muon physics

NASA Astrophysics Data System (ADS)

Gorringe, T. P.; Hertzog, D. W.

2015-09-01

The muon is playing a unique role in sub-atomic physics. Studies of muon decay both determine the overall strength and establish the chiral structure of weak interactions, as well as setting extraordinary limits on charged-lepton-flavor-violating processes. Measurements of the muon's anomalous magnetic moment offer singular sensitivity to the completeness of the standard model and the predictions of many speculative theories. Spectroscopy of muonium and muonic atoms gives unmatched determinations of fundamental quantities including the magnetic moment ratio μμ /μp, lepton mass ratio mμ /me, and proton charge radius rp. Also, muon capture experiments are exploring elusive features of weak interactions involving nucleons and nuclei. We will review the experimental landscape of contemporary high-precision and high-sensitivity experiments with muons. One focus is the novel methods and ingenious techniques that achieve such precision and sensitivity in recent, present, and planned experiments. Another focus is the uncommonly broad and topical range of questions in atomic, nuclear and particle physics that such experiments explore.

A simple scaling law for the equation of state and the radial distribution functions calculated by density-functional theory molecular dynamics

NASA Astrophysics Data System (ADS)

Danel, J.-F.; Kazandjian, L.

2018-06-01

It is shown that the equation of state (EOS) and the radial distribution functions obtained by density-functional theory molecular dynamics (DFT-MD) obey a simple scaling law. At given temperature, the thermodynamic properties and the radial distribution functions given by a DFT-MD simulation remain unchanged if the mole fractions of nuclei of given charge and the average volume per atom remain unchanged. A practical interest of this scaling law is to obtain an EOS table for a fluid from that already obtained for another fluid if it has the right characteristics. Another practical interest of this result is that an asymmetric mixture made up of light and heavy atoms requiring very different time steps can be replaced by a mixture of atoms of equal mass, which facilitates the exploration of the configuration space in a DFT-MD simulation. The scaling law is illustrated by numerical results.

Electronic torsional sound in linear atomic chains: Chemical energy transport at 1000 km/s

NASA Astrophysics Data System (ADS)

Kurnosov, Arkady A.; Rubtsov, Igor V.; Maksymov, Andrii O.; Burin, Alexander L.

2016-07-01

We investigate entirely electronic torsional vibrational modes in linear cumulene chains. The carbon nuclei of a cumulene are positioned along the primary axis so that they can participate only in the transverse and longitudinal motions. However, the interatomic electronic clouds behave as a torsion spring with remarkable torsional stiffness. The collective dynamics of these clouds can be described in terms of electronic vibrational quanta, which we name torsitons. It is shown that the group velocity of the wavepacket of torsitons is much higher than the typical speed of sound, because of the small mass of participating electrons compared to the atomic mass. For the same reason, the maximum energy of the torsitons in cumulenes is as high as a few electronvolts, while the minimum possible energy is evaluated as a few hundred wavenumbers and this minimum is associated with asymmetry of zero point atomic vibrations. Theory predictions are consistent with the time-dependent density functional theory calculations. Molecular systems for experimental evaluation of the predictions are proposed.

Simulating Chiral Magnetic and Separation Effects with Spin-Orbit Coupled Atomic Gases

PubMed Central

Huang, Xu-Guang

2016-01-01

The chiral magnetic and chiral separation effects—quantum-anomaly-induced electric current and chiral current along an external magnetic field in parity-odd quark-gluon plasma—have received intense studies in the community of heavy-ion collision physics. We show that analogous effects occur in rotating trapped Fermi gases with Weyl-Zeeman spin-orbit coupling where the rotation plays the role of an external magnetic field. These effects can induce a mass quadrupole in the atomic cloud along the rotation axis which may be tested in future experiments. Our results suggest that the spin-orbit coupled atomic gases are potential simulators of the chiral magnetic and separation effects. PMID:26868084

N2 Dissociation In The Mesosphere Due To Secondary Electrons During A Solar Proton Event: The Effect On Atomic Nitrogen and Nitric Oxide

NASA Astrophysics Data System (ADS)

Verronen, P. T.; Shematovich, V. I.; Bisikalo, D. V.; Turunen, E.; Ulich, Th.

Solar proton events have an effect on the middle atmospheric odd nitrogen chem- istry. During a solar proton event high energy protons enter Earth's middle atmosphere where they ionize ambient gas. Ionization leads to production of atomic nitrogen, and further to production of nitric oxide, through ion chemistry. In addition, ionization processes produce secondary electrons that, if possessing 9.76 eV or more energy, dissociate N2 providing an additional source of atomic nitrogen. We have calculated mesospheric N2 dissociation rate due to secondary electrons dur- ing a solar proton event. Further, we have studied the effect on atomic nitrogen and nitric oxide at altitudes between 50 and 90 km. It was found that N2 is efficiently dis- sociated in the lower mesosphere by secondary electrons, with rates up to 103 cm-3 s-1 at 50 km. Thus, secondary electrons significantly add to odd nitrogen produc- tion. As a result of N2 dissociation, atomic nitrogen is greatly enhanced in both N(4S) and N(2D) states by 259% and 1220% maximum increases at 50 km, respectively. This further leads to a maximum increase of 16.5% in NO concentration at 61 km via chemical reactions. In our study a Monte Carlo model was used to calculate the total ionization rate and secondary electrons flux due to precipitating protons. These where then used as input to a detailed ion and neutral chemistry model and a steady-state solution was calcu- lated for two cases: With and without N2 dissociation due to secondary electrons.

Neutron Nucleic Acid Crystallography.

PubMed

Chatake, Toshiyuki

2016-01-01

The hydration shells surrounding nucleic acids and hydrogen-bonding networks involving water molecules and nucleic acids are essential interactions for the structural stability and function of nucleic acids. Water molecules in the hydration shells influence various conformations of DNA and RNA by specific hydrogen-bonding networks, which often contribute to the chemical reactivity and molecular recognition of nucleic acids. However, X-ray crystallography could not provide a complete description of structural information with respect to hydrogen bonds. Indeed, X-ray crystallography is a powerful tool for determining the locations of water molecules, i.e., the location of the oxygen atom of H2O; however, it is very difficult to determine the orientation of the water molecules, i.e., the orientation of the two hydrogen atoms of H2O, because X-ray scattering from the hydrogen atom is very small.Neutron crystallography is a specialized tool for determining the positions of hydrogen atoms. Neutrons are not diffracted by electrons, but are diffracted by atomic nuclei; accordingly, neutron scattering lengths of hydrogen and its isotopes are comparable to those of non-hydrogen atoms. Therefore, neutron crystallography can determine both of the locations and orientations of water molecules. This chapter describes the current status of neutron nucleic acid crystallographic research as well as the basic principles of neutron diffraction experiments performed on nucleic acid crystals: materials, crystallization, diffraction experiments, and structure determination.

Atomic force microscopy study on crystal growth of Cu 2+-doped L-arginine phosphate monohydrate crystals

NASA Astrophysics Data System (ADS)

Geng, Y. L.; Xu, D.; Wang, Y. L.; Du, W.; Liu, H. Y.; Zhang, G. H.; Wang, X. Q.; Sun, D. L.

2005-01-01

Sub-steps and defects of the {1 0 0} planes of Cu 2+-doped L-arginine phosphate monohydrate (LAP) crystals are observed by atomic force microscopy. Formation of sub-steps is not due to the stacking faults but a result of single LAP: Cu 2+ molecule acting as growth unit. Two-dimensional (2D) nuclei with the same height as sub-steps occur on the step-edges. Impurities of Cu 2+ ions cause steps bunch and macrosteps formation. Liquid inclusions in the form of long channels form when the macrosteps lose their stability. Numerous small 3D growth hillocks are found in the channels. The extra stress induced by the 3D islands can result in dislocations and steps mismatches.

Scissors Mode of Dipolar Quantum Droplets of Dysprosium Atoms

NASA Astrophysics Data System (ADS)

Ferrier-Barbut, Igor; Wenzel, Matthias; Böttcher, Fabian; Langen, Tim; Isoard, Mathieu; Stringari, Sandro; Pfau, Tilman

2018-04-01

We report on the observation of the scissors mode of a single dipolar quantum droplet. The existence of this mode is due to the breaking of the rotational symmetry by the dipole-dipole interaction, which is fixed along an external homogeneous magnetic field. By modulating the orientation of this magnetic field, we introduce a new spectroscopic technique for studying dipolar quantum droplets. This provides a precise probe for interactions in the system, allowing us to extract a background scattering length for 164Dy of 69 (4 )a0 . Our results establish an analogy between quantum droplets and atomic nuclei, where the existence of the scissors mode is also only due to internal interactions. They further open the possibility to explore physics beyond the available theoretical models for strongly dipolar quantum gases.

Observation of three-photon bound states in a quantum nonlinear medium

NASA Astrophysics Data System (ADS)

Liang, Qi-Yu; Venkatramani, Aditya V.; Cantu, Sergio H.; Nicholson, Travis L.; Gullans, Michael J.; Gorshkov, Alexey V.; Thompson, Jeff D.; Chin, Cheng; Lukin, Mikhail D.; Vuletić, Vladan

2018-02-01

Bound states of massive particles, such as nuclei, atoms, or molecules, constitute the bulk of the visible world around us. By contrast, photons typically only interact weakly. We report the observation of traveling three-photon bound states in a quantum nonlinear medium where the interactions between photons are mediated by atomic Rydberg states. Photon correlation and conditional phase measurements reveal the distinct bunching and phase features associated with three-photon and two-photon bound states. Such photonic trimers and dimers possess shape-preserving wave functions that depend on the constituent photon number. The observed bunching and strongly nonlinear optical phase are described by an effective field theory of Rydberg-induced photon-photon interactions. These observations demonstrate the ability to realize and control strongly interacting quantum many-body states of light.

Applications of Quantum Theory of Atomic and Molecular Scattering to Problems in Hypersonic Flow

NASA Technical Reports Server (NTRS)

Malik, F. Bary

1995-01-01

The general status of a grant to investigate the applications of quantum theory in atomic and molecular scattering problems in hypersonic flow is summarized. Abstracts of five articles and eleven full-length articles published or submitted for publication are included as attachments. The following topics are addressed in these articles: fragmentation of heavy ions (HZE particles); parameterization of absorption cross sections; light ion transport; emission of light fragments as an indicator of equilibrated populations; quantum mechanical, optical model methods for calculating cross sections for particle fragmentation by hydrogen; evaluation of NUCFRG2, the semi-empirical nuclear fragmentation database; investigation of the single- and double-ionization of He by proton and anti-proton collisions; Bose-Einstein condensation of nuclei; and a liquid drop model in HZE particle fragmentation by hydrogen.

Self-bound droplets of a dilute magnetic quantum liquid

NASA Astrophysics Data System (ADS)

Schmitt, Matthias; Wenzel, Matthias; Böttcher, Fabian; Ferrier-Barbut, Igor; Pfau, Tilman

2016-11-01

Self-bound many-body systems are formed through a balance of attractive and repulsive forces and occur in many physical scenarios. Liquid droplets are an example of a self-bound system, formed by a balance of the mutual attractive and repulsive forces that derive from different components of the inter-particle potential. It has been suggested that self-bound ensembles of ultracold atoms should exist for atom number densities that are 108 times lower than in a helium droplet, which is formed from a dense quantum liquid. However, such ensembles have been elusive up to now because they require forces other than the usual zero-range contact interaction, which is either attractive or repulsive but never both. On the basis of the recent finding that an unstable bosonic dipolar gas can be stabilized by a repulsive many-body term, it was predicted that three-dimensional self-bound quantum droplets of magnetic atoms should exist. Here we report the observation of such droplets in a trap-free levitation field. We find that this dilute magnetic quantum liquid requires a minimum, critical number of atoms, below which the liquid evaporates into an expanding gas as a result of the quantum pressure of the individual constituents. Consequently, around this critical atom number we observe an interaction-driven phase transition between a gas and a self-bound liquid in the quantum degenerate regime with ultracold atoms. These droplets are the dilute counterpart of strongly correlated self-bound systems such as atomic nuclei and helium droplets.

Self-bound droplets of a dilute magnetic quantum liquid.

PubMed

Schmitt, Matthias; Wenzel, Matthias; Böttcher, Fabian; Ferrier-Barbut, Igor; Pfau, Tilman

2016-11-10

Self-bound many-body systems are formed through a balance of attractive and repulsive forces and occur in many physical scenarios. Liquid droplets are an example of a self-bound system, formed by a balance of the mutual attractive and repulsive forces that derive from different components of the inter-particle potential. It has been suggested that self-bound ensembles of ultracold atoms should exist for atom number densities that are 10 8 times lower than in a helium droplet, which is formed from a dense quantum liquid. However, such ensembles have been elusive up to now because they require forces other than the usual zero-range contact interaction, which is either attractive or repulsive but never both. On the basis of the recent finding that an unstable bosonic dipolar gas can be stabilized by a repulsive many-body term, it was predicted that three-dimensional self-bound quantum droplets of magnetic atoms should exist. Here we report the observation of such droplets in a trap-free levitation field. We find that this dilute magnetic quantum liquid requires a minimum, critical number of atoms, below which the liquid evaporates into an expanding gas as a result of the quantum pressure of the individual constituents. Consequently, around this critical atom number we observe an interaction-driven phase transition between a gas and a self-bound liquid in the quantum degenerate regime with ultracold atoms. These droplets are the dilute counterpart of strongly correlated self-bound systems such as atomic nuclei and helium droplets.

Strong-coupling phases of the spin-orbit-coupled spin-1 Bose-Hubbard chain: Odd-integer Mott lobes and helical magnetic phases

NASA Astrophysics Data System (ADS)

Pixley, J. H.; Cole, William S.; Spielman, I. B.; Rizzi, Matteo; Das Sarma, S.

2017-10-01

We study the odd-integer filled Mott phases of a spin-1 Bose-Hubbard chain and determine their fate in the presence of a Raman induced spin-orbit coupling which has been achieved in ultracold atomic gases; this system is described by a quantum spin-1 chain with a spiral magnetic field. The spiral magnetic field initially induces helical order with either ferromagnetic or dimer order parameters, giving rise to a spiral paramagnet at large field. The spiral ferromagnet-to-paramagnet phase transition is in a universality class with critical exponents associated with the divergence of the correlation length ν ≈2 /3 and the order-parameter susceptibility γ ≈1 /2 . We solve the effective spin model exactly using the density-matrix renormalization group, and compare with both a large-S classical solution and a phenomenological Landau theory. We discuss how these exotic bosonic magnetic phases can be produced and probed in ultracold atomic experiments in optical lattices.

New Evaluated Semi-Empirical Formula Using Optical Model for 14-15 MeV ( n, t) Reaction Cross Sections

NASA Astrophysics Data System (ADS)

Tel, E.; Durgu, C.; Aydın, A.; Bölükdemir, M. H.; Kaplan, A.; Okuducu, Ş.

2009-12-01

In the next century the world will face the need for new energy sources. Nuclear fusion can be one of the most attractive sources of energy from the viewpoint of safety and minimal environmental impact. Fusion will not produce CO2 or SO2 and thus will not contribute to global warming or acid rain. Achieving acceptable performance for a fusion power system in the areas of economics, safety and environmental acceptability, is critically dependent on performance of the blanket and diverter systems which are the primary heat recovery, plasma purification, and tritium breeding systems. Tritium self-sufficiency must be maintained for a commercial power plant. The hybrid reactor is a combination of the fusion and fission processes. For self-sustaining (D-T) fusion driver tritium breeding ratio should be greater than 1.05. So working out the systematics of ( n, t) reaction cross-sections are of great importance for the definition of the excitation function character for the given reaction taking place on various nuclei at energies up to 20 MeV. In this study, we have calculated non-elastic cross-sections by using optical model for ( n, t) reactions at 14-15 MeV energy. We have investigated the excitation function character and reaction Q-values depending on the asymmetry term effect for the ( n, t) reaction cross-sections. We have obtained new coefficients for the ( n, t) reaction cross-sections. We have suggested semi-empirical formulas including optical model nonelastic effects by fitting two parameters for the ( n, t) reaction cross-sections at 14-15 MeV. We have discussed the odd-even effect and the pairing effect considering binding energy systematic of the nuclear shell model for the new experimental data and new cross-sections formulas ( n, t) reactions developed by Tel et al. We have determined a different parameter groups by the classification of nuclei into even-even, even-odd and odd-even for ( n, t) reactions cross-sections. The obtained cross-section formulas with new coefficients have been discussed and compared with the available experimental data.

Hydrothermal Crystal Growth of Lithium Tetraborate and Lithium Gamma-Metaborate

DTIC Science & Technology

2014-03-27

could be atomic nuclei, the center of mass of some complex—those details are immaterial. Both the rectangle and lozenge form potential cross-sections...HR y d L Figure 10. The red lines are the various contours of solution of 9, using a = 10 Bohr radii and the mass of coefficients on the LHS forced to...absorptivity is significantly below that of the transition metals or the actinides [9]. The lithium borate crystals are therefore a strong candidate for

LEAP 1992: Conference summary

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dover, C.B.

1992-12-01

We present a summary of the many new results in antiproton ({bar p}) physics presented at the LEAP `92 conference, in the areas of meson spectroscopy, {bar N}N scattering, annihilation and spin observables, strangeness and charm production, {bar N} annihilation in nuclei, atomic physics with very low energy {bar p}`s, the exploration of fundamental symmetries and interactions with {bar p} (CP, T, CPT, gravitation), and the prospects for new {bar p} facilities at ultralow energies or energies above the LEAR regime ({ge} 2 GeV/c).

LEAP 1992: Conference summary

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dover, C.B.

1992-12-01

We present a summary of the many new results in antiproton ([bar p]) physics presented at the LEAP '92 conference, in the areas of meson spectroscopy, [bar N]N scattering, annihilation and spin observables, strangeness and charm production, [bar N] annihilation in nuclei, atomic physics with very low energy [bar p]'s, the exploration of fundamental symmetries and interactions with [bar p] (CP, T, CPT, gravitation), and the prospects for new [bar p] facilities at ultralow energies or energies above the LEAR regime ([ge] 2 GeV/c).

Towards a Unified Description of the Electroweak Nuclear Response

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benhar, Omar; Lovato, Alessandro

2015-06-01

We briefly review the growing efforts to set up a unified framework for the description of neutrino interactions with atomic nuclei and nuclear matter, applicable in the broad kinematical region corresponding to neutrino energies ranging between few MeV and few GeV. The emerging picture suggests that the formalism of nuclear many-body theory (NMBT) can be exploited to obtain the neutrino-nucleus cross-sections needed for both the interpretation of oscillation signals and simulations of neutrino transport in compact stars

Positronium formation in e+ plus H- collisions

NASA Technical Reports Server (NTRS)

Straton, Jack C.; Drachman, Richard J.

1990-01-01

Cross sections for positronium formation by capture from the negative hydrogen ion are given. Orthogonalization corrections to the Coulomb (First) Born Approximation (CBA) differential and total cross sections are calculated using approximate H- wave functions of both Lowdin and Chandrasekhar. Various methods of orthogonalizing the unbound projectile to the possible bound states are considered. It is found that treating the atomic nuclei as if they were isotopic spin projections of a single type of nucleon gives cross sections that are an improvement over the CBA.

Correlation of nonorthogonality of best hybrid bond orbitals with bond strength of orthogonal orbitals

PubMed Central

Pauling, Linus

1976-01-01

An expression is derived for the bond length of two spd orbitals with maximum values in two directions forming a given bond angle by consideration of the nonorthogonality integral of two best orbitals in these directions. This equation is equivalent to the expression derived by formulating the pair of orthogonal orbitals. Similar expressions are derived for spdf orbitals. Applications are made to icosahedral and cuboctahedral bonds and to the packing of nucleons in atomic nuclei. PMID:16578736

Correlation of nonorthogonality of best hybrid bond orbitals with bond strength of orthogonal orbitals.

PubMed

Pauling, L

1976-02-01

An expression is derived for the bond length of two spd orbitals with maximum values in two directions forming a given bond angle by consideration of the nonorthogonality integral of two best orbitals in these directions. This equation is equivalent to the expression derived by formulating the pair of orthogonal orbitals. Similar expressions are derived for spdf orbitals. Applications are made to icosahedral and cuboctahedral bonds and to the packing of nucleons in atomic nuclei.

Simulation of dependence of the cross section of deuterons beam fragmentation into cumulative pions and protons on the mass of the target nucleus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Litvinenko, A. G., E-mail: alitvin@jinr.ru; Litvinenko, E. I.

2015-03-15

We have studied the mechanisms influencing production of cumulative pions and protons in the fragmentation of the incident deuterons into cumulative pions and protons emitted at zero angle. We argue that the peripheral dependence on the atomic mass of the target nucleus, which was obtained in the experiments for medium and heavy nuclei, can be explained by scattering on target nucleons without introducing additional parameters.

Nuclear physics from lattice QCD at strong coupling.

PubMed

de Forcrand, Ph; Fromm, M

2010-03-19

We study numerically the strong coupling limit of lattice QCD with one flavor of massless staggered quarks. We determine the complete phase diagram as a function of temperature and chemical potential, including a tricritical point. We clarify the nature of the low temperature dense phase, which is strongly bound "nuclear" matter. This strong binding is explained by the nuclear potential, which we measure. Finally, we determine, from this first-principles limiting case of QCD, the masses of "atomic nuclei" up to A=12 "carbon".

Influence of target thickness on the release of radioactive atoms

NASA Astrophysics Data System (ADS)

Guillot, Julien; Roussière, Brigitte; Tusseau-Nenez, Sandrine; Barré-Boscher, Nicole; Borg, Elie; Martin, Julien

2017-03-01

Nowadays, intense exotic beams are needed in order to study nuclei with very short half-life. To increase the release efficiency of the fission products, all the target characteristics involved must be improved (e.g. chemical composition, dimensions, physicochemical properties such as grain size, porosity, density…). In this article, we study the impact of the target thickness. Released fractions measured from graphite and uranium carbide pellets are presented as well as Monte-Carlo simulations of the Brownian motion.

Spin-dependent γ softness or triaxiality in even-even 132-138Nd nuclei

NASA Astrophysics Data System (ADS)

Chai, Qing-Zhen; Wang, Hua-Lei; Yang, Qiong; Liu, Min-Liang

2015-02-01

The properties of γ instability in rapidly rotating even-even 132-138Nd isotopes have been investigated using the pairing-deformation self-consistent total-Routhian-surface calculations in a deformation space of (β2, γ, β4). It is found that even-even 134-138Nd nuclei exhibit triaxiality in both ground and excited states, even up to high-spin states. The lightest isotope possesses a well-deformed prolate shape without a γ deformation component. The current numerical results are compared with previous calculations and available observables such as quadrupole deformation β2 and the feature of γ-band levels, showing basically a general agreement with the observed trend of γ correlations (e.g. the pattern of the odd-even energy staggering of the γ band). The existing differences between theory and experiment are analyzed and discussed briefly. Supported by National Natural Science Foundation of China (10805040,11175217), Foundation and Advanced Technology Research Program of Henan Province(132300410125) and S & T Research Key Program of Henan Province Education Department (13A140667)

Effectively-truncated large-scale shell-model calculations and nuclei around 100Sn

NASA Astrophysics Data System (ADS)

Gargano, A.; Coraggio, L.; Itaco, N.

2017-09-01

This paper presents a short overview of a procedure we have recently introduced, dubbed the double-step truncation method, which is aimed to reduce the computational complexity of large-scale shell-model calculations. Within this procedure, one starts with a realistic shell-model Hamiltonian defined in a large model space, and then, by analyzing the effective single particle energies of this Hamiltonian as a function of the number of valence protons and/or neutrons, reduced model spaces are identified containing only the single-particle orbitals relevant to the description of the spectroscopic properties of a certain class of nuclei. As a final step, new effective shell-model Hamiltonians defined within the reduced model spaces are derived by way of a unitary transformation of the original large-scale Hamiltonian. A detailed account of this transformation is given and the merit of the double-step truncation method is illustrated by discussing few selected results for 96Mo, described as four protons and four neutrons outside 88Sr. Some new preliminary results for light odd-tin isotopes from A = 101 to 107 are also reported.

Experimental results on antiproton-nuclei annihilation cross section at very low energies

NASA Astrophysics Data System (ADS)

Aghai-Khozani, H.; Barna, D.; Corradini, M.; Hayano, R.; Hori, M.; Kobayashi, T.; Leali, M.; Lodi-Rizzini, E.; Mascagna, V.; Prest, M.; Soter, A.; Todoroki, K.; Vallazza, E.; Venturelli, L.; Zurlo, N.

2014-03-01

Investigating the antiproton cross section on nuclei at low energies (1 eV - 1 MeV) is of great interest for fundamental cosmology and nuclear physics as well. The process is of great relevance for the models which try to explain the matter/antimatter asymmetry in the universe assuming the existence of the so-called "island" where antinucleon-nucleon annihilations occur in the border region [1]. For the nuclear physics point of view, the annihilation process is considered a useful tool to evaluate the neutron/proton ratio probing the external region of the nucleus. Moreover, the cross section measured at LEAR in the 80s-90s showed an unexpected behaviour for energies below 1 MeV. The results showed a saturation with the atomic mass number against the A2/3 trend which is known for higher energies. The ASACUSA collaboration at CERN measured 5.3 MeV antiproton annihilation cross section on different nuclei whose results demonstrated to be consistent with the black-disk model with the Coulomb correction [2]. So far, experimental limits prevented the data acquisition for energies below 1 MeV. In 2012 the 100 keV region has been investigated for the first time [3]. We present here the results of the experiment.

Accelerated path integral methods for atomistic simulations at ultra-low temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uhl, Felix, E-mail: felix.uhl@rub.de; Marx, Dominik; Ceriotti, Michele

2016-08-07

Path integral methods provide a rigorous and systematically convergent framework to include the quantum mechanical nature of atomic nuclei in the evaluation of the equilibrium properties of molecules, liquids, or solids at finite temperature. Such nuclear quantum effects are often significant for light nuclei already at room temperature, but become crucial at cryogenic temperatures such as those provided by superfluid helium as a solvent. Unfortunately, the cost of converged path integral simulations increases significantly upon lowering the temperature so that the computational burden of simulating matter at the typical superfluid helium temperatures becomes prohibitive. Here we investigate how accelerated pathmore » integral techniques based on colored noise generalized Langevin equations, in particular the so-called path integral generalized Langevin equation thermostat (PIGLET) variant, perform in this extreme quantum regime using as an example the quasi-rigid methane molecule and its highly fluxional protonated cousin, CH{sub 5}{sup +}. We show that the PIGLET technique gives a speedup of two orders of magnitude in the evaluation of structural observables and quantum kinetic energy at ultralow temperatures. Moreover, we computed the spatial spread of the quantum nuclei in CH{sub 4} to illustrate the limits of using such colored noise thermostats close to the many body quantum ground state.« less

Isomer spectroscopy of neutron-rich 168Tb 103

DOE PAGES

Gurgi, L. A.; Regan, P. H.; Söderström, P. -A.; ...

2016-12-29

In-flight fission of a 345 MeV per nucleon 238U primary beam on a 2 mm thick 9Be target has been used to produce and study the decays of a range of neutron-rich nuclei centred around the doubly mid-shell nucleus 170Dy at the RIBF Facility, RIKEN, Japan. The produced secondary fragments of interest were identified event-by-event using the BigRIPS separator. The fragments were implanted into the WAS3ABI position sensitive silicon active stopper which allowed pixelated correlations between implants and their subsequent β-decay. Discrete γ-ray transitions emitted following decays from either metastable states or excited states populated following beta decay were identifiedmore » using the 84 coaxial high-purity germanium (HPGe) detectors of the EURICA spectrometer, which was complemented by 18 additional cerium-doped lanthanum bromide (LaBr 3) fast-timing scintillation detectors from the FATIMA collaboration. This paper presents the internal decay of a metastable isomeric excited state in the odd-odd nucleus 168Tb, which corresponds to a single proton-neutron hole configuration in the valence maximum nucleus 170Dy. These data represent the first information on excited states in this nucleus, which is the most neutron-rich odd-odd isotope of terbium (Z = 65) studied to date. Here, Nilsson configurations associated with an axially symmetric, prolate-deformed nucleus are proposed for the 168Tb ground state the observed isomeric state by comparison with Blocked BCS-Nilsson calculations.« less

Isomer spectroscopy of neutron-rich 168Tb103

NASA Astrophysics Data System (ADS)

Gurgi, L. A.; Regan, P. H.; Söderström, P.-A.; Watanabe, H.; Walker, P. M.; Podolyák, Zs.; Nishimura, S.; Berry, T. A.; Doornenbal, P.; Lorusso, G.; Isobe, T.; Baba, H.; Xu, Z. Y.; Sakurai, H.; Sumikama, T.; Catford, W. N.; Bruce, A. M.; Browne, F.; Lane, G. J.; Kondev, F. G.; Odahara, A.; Wu, J.; Liu, H. L.; Xu, F. R.; Korkulu, Z.; Lee, P.; Liu, J. J.; Phong, V. H.; Yag, A.; Zhang, G. X.; Alharbi, T.; Carroll, R. J.; Chae, K. Y.; Dombradi, Zs.; Estrade, A.; Fukuda, N.; Griffin, C.; Ideguchi, E.; Inabe, N.; Kanaoka, H.; Kojouharov, I.; Kubo, T.; Kubono, S.; Kurz, N.; Kuti, I.; Lalkovski, S.; Lee, E. J.; Lee, C. S.; Lotay, G.; Moon, C.-B.; Nishizuka, I.; Nita, C. R.; Patel, Z.; Roberts, O. J.; Schaffner, H.; Shand, C. M.; Suzuki, H.; Takeda, H.; Terashima, S.; Vajta, Zs.; Yoshida, S.; Valiente-Dòbon, J. J.

2017-11-01

In-flight fission of a 345 MeV per nucleon 238U primary beam on a 2 mm thick 9Be target has been used to produce and study the decays of a range of neutron-rich nuclei centred around the doubly mid-shell nucleus 170Dy at the RIBF Facility, RIKEN, Japan. The produced secondary fragments of interest were identified event-by-event using the BigRIPS separator. The fragments were implanted into the WAS3ABI position sensitive silicon active stopper which allowed pixelated correlations between implants and their subsequent β-decay. Discrete γ-ray transitions emitted following decays from either metastable states or excited states populated following beta decay were identified using the 84 coaxial high-purity germanium (HPGe) detectors of the EURICA spectrometer, which was complemented by 18 additional cerium-doped lanthanum bromide (LaBr3) fast-timing scintillation detectors from the FATIMA collaboration. This paper presents the internal decay of a metastable isomeric excited state in the odd-odd nucleus 168Tb, which corresponds to a single proton-neutron hole configuration in the valence maximum nucleus 170Dy. These data represent the first information on excited states in this nucleus, which is the most neutron-rich odd-odd isotope of terbium (Z=65) studied to date. Nilsson configurations associated with an axially symmetric, prolate-deformed nucleus are proposed for the 168Tb ground state the observed isomeric state by comparison with Blocked BCS-Nilsson calculations.

Extracting nuclear sizes of medium to heavy nuclei from total reaction cross sections

NASA Astrophysics Data System (ADS)

Horiuchi, W.; Hatakeyama, S.; Ebata, S.; Suzuki, Y.

2016-04-01

Background: Proton and neutron radii are fundamental quantities of atomic nuclei. To study the sizes of short-lived unstable nuclei, there is a need for an alternative to electron scattering. Purpose: The recent paper by Horiuchi et al. [Phys. Rev. C 89, 011601(R) (2014)], 10.1103/PhysRevC.89.011601 proposed a possible way of extracting the matter and neutron-skin thickness of light- to medium-mass nuclei using total reaction cross section, σR. The analysis is extended to medium to heavy nuclei up to lead isotopes with due attention to Coulomb breakup contributions as well as density distributions improved by paring correlation. Methods: We formulate a quantitative calculation of σR based on the Glauber model including the Coulomb breakup. To substantiate the treatment of the Coulomb breakup, we also evaluate the Coulomb breakup cross section due to the electric dipole field in a canonical-basis-time-dependent-Hartree-Fock-Bogoliubov theory in the three-dimensional coordinate space. Results: We analyze σR's of 103 nuclei with Z =20 , 28, 40, 50, 70, and 82 incident on light targets, H,21, 4He, and 12C. Three kinds of Skyrme interactions are tested to generate those wave functions. To discuss possible uncertainty due to the Coulomb breakup, we examine its dependence on the target, the incident energy, and the Skyrme interaction. The proton is a most promising target for extracting the nuclear sizes as the Coulomb excitation can safely be neglected. We find that the so-called reaction radius, aR=√{σR/π } , for the proton target is very well approximated by a linear function of two variables, the matter radius and the skin thickness, in which three constants depend only on the incident energy. We quantify the accuracy of σR measurements needed to extract the nuclear sizes. Conclusions: The proton is the best target because, once the incident energy is set, its aR is very accurately determined by only the matter radius and neutron-skin thickness. If σR's at different incident energies are measured, one can determine both the proton and neutron radii for unstable nuclei as well. The total reaction cross sections calculated in this paper are given as Supplemental Material for the sake of future measurements.

Development of a Plutonium Ceramic Target for the MASHA Separator

NASA Astrophysics Data System (ADS)

Shaughnessy, D. A.; Moody, K. J.; Kenneally, J. M.; Wild, J. F.; Stoyer, M. A.; Lougheed, R. W.; Yeremin, A. V.; Oganessian, Yu. Ts.

2004-04-01

We are participating in the development of the target for the MASHA (Mass Analyzer of Super Heavy Atoms) on-line mass separator in Dubna. Along with recent upgrades of the U400 cyclotron, MASHA will provide for at least a ten-fold increase in the production- and-detection rate for element 114 atoms, and will allow us to measure their atomic masses precisely. The MASHA separator will employ a thick Pu ceramic target capa- ble of tolerating temperatures in the vicinity of 2000 C without vaporizing the actinide compound. Reaction products will diffuse out of the target and will drift to an ECR ion source after which they will be transported through the separator and will impinge on a position-sensitive focal-plane detector array. Furthermore, operation of the MASHA hot target/ion source combination will provide chemical volatility information that will support our assignment of an atomic number of 114 to these nuclei. Taken together, these experiments on MASHA will allow us to make measurements that will cement our identification of element 114 and provide for future experiments in which the chemical properties of the heaviest elements are studied.

Magnetizabilities of relativistic hydrogenlike atoms in some arbitrary discrete energy eigenstates

NASA Astrophysics Data System (ADS)

Stefańska, Patrycja

2016-03-01

We present the results of numerical calculations of magnetizability (χ) of the relativistic one-electron atoms with a pointlike, spinless and motionless nuclei of charge Ze. Exploiting the analytical formula for χ recently derived by us Stefańska (2015), valid for an arbitrary discrete energy eigenstate, we have found the values of the magnetizability for the ground state and for the first and the second set of excited states (i.e.: 2s1/2, 2p1/2, 2p3/2, 3s1/2, 3p1/2, 3p3/2, 3d3/2, and 3d5/2) of the Dirac one-electron atom. The results for ions with the atomic number 1 ⩽ Z ⩽ 137 are given in 14 tables. The comparison of the numerical values of magnetizabilities for the ground state and for each state belonging to the first set of excited states of selected hydrogenlike ions, obtained with the use of two different values of the fine-structure constant, i.e.: α-1 = 137.035 999 139 (CODATA 2014) and α-1 = 137.035 999 074 (CODATA 2010), is also presented.

Fast Atom Ionization in Strong Electromagnetic Radiation

NASA Astrophysics Data System (ADS)

Apostol, M.

2018-05-01

The Goeppert-Mayer and Kramers-Henneberger transformations are examined for bound charges placed in electromagnetic radiation in the non-relativistic approximation. The consistent inclusion of the interaction with the radiation field provides the time evolution of the wavefunction with both structural interaction (which ensures the bound state) and electromagnetic interaction. It is shown that in a short time after switching on the high-intensity radiation the bound charges are set free. In these conditions, a statistical criterion is used to estimate the rate of atom ionization. The results correspond to a sudden application of the electromagnetic interaction, in contrast with the well-known ionization probability obtained by quasi-classical tunneling through classically unavailable non-stationary states, or other equivalent methods, where the interaction is introduced adiabatically. For low-intensity radiation the charges oscillate and emit higher-order harmonics, the charge configuration is re-arranged and the process is resumed. Tunneling ionization may appear in these circumstances. Extension of the approach to other applications involving radiation-induced charge emission from bound states is discussed, like ionization of molecules, atomic clusters or proton emission from atomic nuclei. Also, results for a static electric field are included.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, L. W.; Franceschetti, A.; Zunger, A.

We have developed a "linear combination of bulk bands" method that permits atomistic, pseudopotential electronic structure calculations for .apprx.10(sup6) atom nanostructures. Application to (GaAs)n/A1As)n (001) superlattices (SL's) reveals even-odd oscillations in the ..Gamma..-X coupling magnitude Vrx(n), which vanishes for n = odd, even for abrupt and segregated SL's, respectively. Surprisingly, in contrast with recent expectations, OD quantum dots are found here to have a smaller ..Gamma..-X coupling than equivalent 2D SL's. Our analysis shows that for large quantum dots this is largely due to the existence of level repulsion from many X states.

Self-Assembly, Supramolecular Organization, and Phase Behavior of L-Alanine Alkyl Esters (n = 9-18) and Characterization of Equimolar L-Alanine Lauryl Ester/Lauryl Sulfate Catanionic Complex.

PubMed

Sivaramakrishna, D; Swamy, Musti J

2015-09-08

A homologous series of l-alanine alkyl ester hydrochlorides (AEs) bearing 9-18 C atoms in the alkyl chain have been synthesized and characterized with respect to self-assembly, supramolecular structure, and phase transitions. The CMCs of AEs bearing 11-18 C atoms were found to range between 0.1 and 10 mM. Differential scanning calorimetric (DSC) studies showed that the transition temperatures (Tt), enthalpies (ΔHt) and entropies (ΔSt) of AEs in the dry state exhibit odd-even alternation, with the odd-chain-length compounds having higher Tt values, but the even-chain-length homologues showing higher values of ΔHt and ΔSt. In DSC measurements on hydrated samples, carried out at pH 5.0 and pH 10.0 (where they exist in cationic and neutral forms, respectively), compounds with 13-18 C atoms in the alkyl chain showed sharp gel-to-liquid crystalline phase transitions, and odd-even alternation was not seen in the thermodynamic parameters. The molecular structure, packing properties, and intermolecular interactions of AEs with 9 and 10 C atoms in the alkyl chain were determined by single crystal X-ray diffraction, which showed that the alkyl chains are packed in a tilted interdigitated bilayer format. d-Spacings obtained from powder X-ray diffraction studies exhibited a linear dependence on the alkyl chain length, suggesting that the other AEs also adopt an interdigitated bilayer structure. Turbidimetric, fluorescence spectroscopic, and isothermal titration calorimetric (ITC) studies established that in aqueous dispersions l-alanine lauryl ester hydrochloride (ALE·HCl) and sodium dodecyl sulfate (SDS) form an equimolar complex. Transmission electron microscopic and DSC studies indicate that the complex exists as unilamellar liposomes, which exhibit a sharp phase transition at ∼39 °C. The aggregates were disrupted at high pH, suggesting that the catanionic complex would be useful to develop a base-labile drug delivery system. ITC studies indicated that ALE·HCl forms a strong complex with DNA, suggesting that the AEs may find use in DNA therapeutics as well.

Dipole response of neutron-rich Sn isotopes

NASA Astrophysics Data System (ADS)

Klimkiewicz, A.; Adrich, P.; Boretzky, K.; Fallot, M.; Aumann, T.; Cortina-Gil, D.; Datta Pramanik, U.; Elze, Th. W.; Emling, H.; Geissel, H.; Hellstroem, M.; Jones, K. L.; Kratz, J. V.; Kulessa, R.; Leifels, Y.; Nociforo, C.; Palit, R.; Simon, H.; Surowka, G.; Sümmerer, K.; Typel, S.; Walus, W.

2007-05-01

The neutron-rich isotopes 129-133Sn were studied in a Coulomb excitation experiment at about 500 AMeV using the FRS-LAND setup at GSI. From the exclusive measurement of all projectile-like particles following the excitation and decay of the projectile in a high-Z target, the energy differential cross section can be extracted. At these beam energies dipole transitions are dominating, and within the semi-classical approach the Coulomb excitation cross sections can be transformed into photoabsorption cross sections. In contrast to stable Sn nuclei, a substantial fraction of dipole strength is observed at energies below the giant dipole resonance (GDR). For 130Sn and 132Sn this strength is located in a peak-like structure around 10 MeV excitation energy and exhibits a few percent of the Thomas-Reiche Kuhn (TRK) sum-rule strength. Several calculations predict the appearance of dipole strength at low excitation energies in neutron-rich nuclei. This low-lying strength is often referred to as pygmy dipole resonance (PDR) and, in a macroscopic picture, is discussed in terms of a collective oscillation of excess neutrons versus the core nucleons. Moreover, a sharp rise is observed at the neutron separation threshold around 5 MeV for the odd isotopes. A possible contribution of 'threshold strength', which can be described within the direct-breakup model is discussed. The results for the neutron-rich Sn isotopes are confronted with results on stable nuclei investigated in experiments using real photons.

Atomic Decay Data for Modeling K Lines of Iron Peak and Light Odd-Z Elements*

NASA Technical Reports Server (NTRS)

Palmeri, P.; Quinet, P.; Mendoza, C.; Bautista, M. A.; Garcia, J.; Witthoeft, M. C.; Kallman, T. R.

2012-01-01

Complete data sets of level energies, transition wavelengths, A-values, radiative and Auger widths and fluorescence yields for K-vacancy levels of the F, Na, P, Cl, K, Sc, Ti, V, Cr, Mn, Co, Cu and Zn isonuclear sequences have been computed by a Hartree-Fock method that includes relativistic corrections as implemented in Cowan's atomic structure computer suite. The atomic parameters for more than 3 million fine-structure K lines have been determined. Ions with electron number N greater than 9 are treated for the first time, and detailed comparisons with available measurements and theoretical data for ions with N less than or equal to 9 are carried out in order to estimate reliable accuracy ratings.

Gamma ray heating and neutrino cooling rates due to weak interaction processes on sd-shell nuclei in stellar cores

NASA Astrophysics Data System (ADS)

Fayaz, Muhammad; Nabi, Jameel-Un; Majid, Muhammad

2017-07-01

Gamma ray heating and neutrino cooling rates, due to weak interaction processes, on sd-shell nuclei in stellar core are calculated using the proton neutron quasiparticle random phase approximation theory. The recent extensive experimental mass compilation of Wang et al. (Chin. Phys. C 36:1603, 2012), other improved model input parameters including nuclear quadrupole deformation (Raman et al. in At. Data Nucl. Data Tables 78(1):1-128, 2001; Möller et al. in At. Data Nucl. Data Tables 109:1-204, 2016) and physical constants are taken into account in the current calculation. The purpose of this work is two fold, one is to improve the earlier calculation of weak rates performed by Nabi and Klapdor-Kleingrothaus (At. Data Nucl. Data Tables 71:149, 1999a) using the same theory. We further compare our results with previous calculations. The selected sd-shell nuclei, considered in this work, are of special interest for the evolution of O-Ne-Mg core in 8-10 M_{⊙} stars due to competitive gamma ray heating rates and cooling by URCA processes. The outcome of these competitions is to determine, whether the stars end up as a white dwarf (Nabi in Phys. Rev. C 78(4):045801, 2008b), an electron-capture supernova (Jones et al. in Astrophys. J. 772(2):150, 2013) or Fe core-collapse supernova (Suzuki et al. in Astrophys. J. 817(2):163, 2016). The selected sd-shell nuclei for calculation of associated weak-interaction rates include ^{20,23}O, ^{20,23}F, ^{20,23,24}Ne, {}^{20,23-25}Na, and {}^{23-25}Mg. The cooling and heating rates are calculated for density range (10 ≤ ρ (g cm^{-3}) ≤ 10^{11}) and temperature range (0.01× 109≤ T(K)≤ 30× 109). The calculated gamma heating rates are orders of magnitude bigger than the shell model rates (except for ^{25}Mg at low densities). At high temperatures the gamma heating rates are in reasonable agreement. The calculated cooling rates are up to an order of magnitude bigger for odd-A nuclei.

ToF diagnostic of Tin resonant laser photoionization in SPES laser offline laboratory

NASA Astrophysics Data System (ADS)

Scarpa, D.; Fedorov, D.; Andrighetto, A.; Mariotti, E.; Nicolosi, P.; Sottili, L.; Tomaselli, A.; Cecchi, R.; Stiaccini, L.

2016-09-01

Tin is the principal element of interest in the SPES ISOL facility, which is under construction at Legnaro INFN Laboratories. Atomic nuclei have a shell structure in which nuclei with \\textquoteleft magic numbers\\textquoteright of protons and neutrons are analogous to the noble gasses in atomic physics. In particular, recent theoretical studies, reveal double-magic nature of radioactive 132Sn. For this reason the nuclear physics community demonstrated, in the last years, a huge interest to produce and study this radioactive neutron rich isotope. Experiments on Tin laser resonant ionization have been performed in the offline SPES laser laboratory to investigate the capability of the new home-made Time of Flight (ToF) mass spectrometer. Several three-step, two color ionization schemes have been tested by comparing fast and slow optogalvanic signals from a Tin Hollow Cathode Lamp (HCL) and Time of Flight signals from the spectrometer. By scanning the wavelength of one of the two dye lasers across the specific resonance, comparisons of ionization signals from both the ToF and the HCL have been made, finding perfect agreement. Furthermore, with the mass spectrometer, resolved peaks of all the natural Tin isotopes have been detected. The natural abundances extracted from these measurements are in agreement with the table values for Tin isotopes. This work, with comparison of OGE and ToF signals, confirm the fully functional SPES offline laser laboratory capability in order to develop scheme studies also for the other possible Radioactive Ion Beam (RIB) elements.

Van der Waals epitaxial growth of two-dimensional single-crystalline GaSe domains on graphene

DOE PAGES

Li, Xufan; Basile, Leonardo; Huang, Bing; ...

2015-07-22

Two-dimensional (2D) van der Waals (vdW) heterostructures are a family of artificially-structured materials that promise tunable optoelectronic properties for devices with enhanced functionalities. Compared to stamping, direct epitaxy of vdW heterostructures is ideal for clean interlayer interfaces and scalable device fabrication. Here, we explore the synthesis and preferred orientations of 2D GaSe atomic layers on graphene (Gr) by vdW epitaxy. Guided by the wrinkles on graphene, GaSe nuclei form that share a predominant lattice orientation. Due to vdW epitaxial growth many nuclei grow as perfectly aligned crystals and coalesce to form large (tens of microns), single-crystal flakes. Through theoretical investigationsmore » of interlayer energetics, and measurements of preferred orientations by atomic-resolution STEM and electron diffraction, a 10.9 interlayer rotation of the GaSe lattice with respect to the underlying graphene is found to be the most energetically preferred vdW heterostructure with the largest binding energy and the longest-range ordering. These GaSe/Gr vdW heterostructures exhibit an enhanced Raman E 2 1g band of monolayer GaSe along with highly-quenched photoluminescence due to strong charge transfer. Despite the very large lattice mismatch of GaSe/Gr through vdW epitaxy, the predominant orientation control and convergent formation of large single-crystal flakes demonstrated here is promising for the scalable synthesis of large-area vdW heterostructures for the development of new optical and optoelectronic devices.« less

Van der Waals epitaxial growth of two-dimensional single-crystalline GaSe domains on graphene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Xufan; Basile, Leonardo; Huang, Bing

Two-dimensional (2D) van der Waals (vdW) heterostructures are a family of artificially-structured materials that promise tunable optoelectronic properties for devices with enhanced functionalities. Compared to stamping, direct epitaxy of vdW heterostructures is ideal for clean interlayer interfaces and scalable device fabrication. Here, we explore the synthesis and preferred orientations of 2D GaSe atomic layers on graphene (Gr) by vdW epitaxy. Guided by the wrinkles on graphene, GaSe nuclei form that share a predominant lattice orientation. Due to vdW epitaxial growth many nuclei grow as perfectly aligned crystals and coalesce to form large (tens of microns), single-crystal flakes. Through theoretical investigationsmore » of interlayer energetics, and measurements of preferred orientations by atomic-resolution STEM and electron diffraction, a 10.9 interlayer rotation of the GaSe lattice with respect to the underlying graphene is found to be the most energetically preferred vdW heterostructure with the largest binding energy and the longest-range ordering. These GaSe/Gr vdW heterostructures exhibit an enhanced Raman E 2 1g band of monolayer GaSe along with highly-quenched photoluminescence due to strong charge transfer. Despite the very large lattice mismatch of GaSe/Gr through vdW epitaxy, the predominant orientation control and convergent formation of large single-crystal flakes demonstrated here is promising for the scalable synthesis of large-area vdW heterostructures for the development of new optical and optoelectronic devices.« less

TiO(2) doping by hydroxyurea at the nucleation stage: towards a new photocatalyst in the visible spectral range.

PubMed

Azouani, R; Tieng, S; Chhor, K; Bocquet, J-F; Eloy, P; Gaigneaux, E M; Klementiev, K; Kanaev, A V

2010-10-07

We report an original method of preparation of OCN-doped TiO(2) for photocatalysis in the visible spectral range. The preparation is achieved by a sol-gel route using titanium tetraisopropoxide precursor. Special attention was paid to fluid micromixing, which enables homogeneous reaction conditions in the reactor bulk and monodispersity of the produced clusters/nanoparticles. The dopant hydroxyurea (HyU, CH(4)N(2)O(2)) is injected into the reactive fluid at the nucleation stage, which lasts tens of milliseconds. The doping results in a strong yellow coloration of the nanocolloids due to the absorption band in the spectral range 380-550 nm and accelerates the aggregation kinetics of both nuclei at the induction stage and sub-nuclei units (clusters) at the nucleation stage. FTIR, Raman and UV-visible absorption analyses show the formation of a stable HyU-TiO(2) complex. EXAFS spectra indicate no appreciable changes of the first-shell Ti atom environment. The doping agent takes available surface sites of TiO(2) clusters/nanoparticles attaining ∼10% molar loading. The reaction kinetics then accelerates due to a longer collisional lifetime between nanoparticles induced by the formation of a weak [double bond, length as m-dash]OTi bond. The OCN-group bonding to titanium atoms produces a weakening of the C[double bond, length as m-dash]O double bond and a strengthening of the C-N and N-O bonds.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allmond, J. M.; Wood, J. L.

We extracted empirical moments of inertia, J1, J2, J3, of atomic nuclei with E(4more » $$+\\atop{1}$$)/E(2$$+\\atop{1}$$ ) > 2.7 from experimental 2$$+\\atop{g,y}$$, energies and electric quadrupole matrix elements, determined from multi- step Coulomb excitation data, and the results are compared to expectations based on rigid and irro- tational inertial flow. Only by having the signs of the E2 matrix elements, i.e., <2$$+\\atop{g}$$ ||M (E2)||2$$+\\atop{g}$$> and <0$$+\\atop{g}$$ ||M (E2)||2$$+\\atop{g}$$> < 2$$+\\atop{g}$$ ||M (E2)||2$$+\\atop{γ}$$> <2$$+\\atop{γ}$$ ||M (E2)||0$$+\\atop{g}$$> , can a unique solution to all three components of the inertia tensor of an asymmetric top be obtained. And while the absolute moments of inertia fall between the rigid and irrotational values as expected, the relative moments of inertia appear to be qualitatively consistent with the β 2 sin 2(γ ) dependence of the Bohr Hamiltonian which originates from a SO(5) in- variance. A better understanding of inertial flow is central to improving collective models, particularly hydrodynamic-based collective models. The results suggest that a better description of collective dynamics and inertial flow for atomic nuclei is needed. The inclusion of vorticity degrees of freedom may provide a path forward. This is our first report of empirical moments of inertia for all three axes and the results should challenge both collective and microscopic descriptions of inertial flow.« less

Solitonic excitations in collisions of superfluid nuclei a qualitatively new phenomenon distinct from the Josephson effect

NASA Astrophysics Data System (ADS)

Sekizawa, Kazuyuki; Wlazłowski, Gabriel; Magierski, Piotr

2017-11-01

Recently, we have reported a novel role of pairing in low-energy heavy ion reactions at energies above the Coulomb barrier, which may have a detectable impact on reaction outcomes, such as the kinetic energy of fragments and the fusion cross section [arXiv:1611.10261, arXiv:1702.00069]. The phenomenon mimics the one studied experimentally with ultracold atomic gases, where two clouds of fermionic superfluids with different phases of the pairing fields are forced to merge, inducing various excitation modes of the pairing field. Although it originates from the phase difference of the pairing fields, the physics behind it is markedly different from the so-called Josephson effect. In this short contribution, we will briefly outline the results discussed in our recent papers and explain relations with the field of ultracold atomic gases.

And So Ad Infinitum: The Search for Quark and Lepton Substructure

DOE PAGES

Lincoln, Don

2018-04-01

The Victorian era mathematician, Augustus de Morgan wrote, “Great fleas have little fleas upon their backs to bite ‘em, And little fleas have lesser fleas, and so ad infinitum.” This parody of Jonathan Swift’s 1733 poem On Poetry: A Rhapsody arose from a literary history, but it is rather easy to see a metaphor for nature in these words. The saga of the search for the ultimate constituents of matter has long been one of finding a seemingly fundamental structure that, in turn, was found to be made of even smaller building blocks. Matter is made of molecules. Molecules aremore » in turn made of atoms, which are themselves made of electrons and atomic nuclei. Furthermore, the nucleus consists of protons and neutrons, and these nucleons are composed of quarks.« less

NMR Spectra of Oriented Samples of Intercalated Fluorographite and 19F Chemical Shielding Anisotropy of the CIF 3 Molecule

NASA Astrophysics Data System (ADS)

Panich, A. M.

The analysis of 19F NMR spectra of polycrystalline and partially oriented samples of fluorinated graphite (C 2F) n intercalated with chlorine trifluoride has been carried out. Molecular mobility results in almost complete averaging of the dipole-dipole interactions of nuclei, while the essential chemical shielding anisotropy (CSA) is manifested. There is suggested molecular rotation about its C2 axes, which in turn rotates about the normal to the graphite plane. The CSA (σ || - σ ⊥) is determined to be 510 and -640 ppm, respectively, for the two inequivalent fluorine atoms of the molecule. The effect of the "antiparamagnetic" shielding leading to inversion of the chemical shielding tenser [(σ || - σ ⊥) < 0] for the equatorial F atom and anomalous line disposition in the NMR spectrum is discussed.

And So Ad Infinitum: The Search for Quark and Lepton Substructure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lincoln, Don

The Victorian era mathematician, Augustus de Morgan wrote, “Great fleas have little fleas upon their backs to bite ‘em, And little fleas have lesser fleas, and so ad infinitum.” This parody of Jonathan Swift’s 1733 poem On Poetry: A Rhapsody arose from a literary history, but it is rather easy to see a metaphor for nature in these words. The saga of the search for the ultimate constituents of matter has long been one of finding a seemingly fundamental structure that, in turn, was found to be made of even smaller building blocks. Matter is made of molecules. Molecules aremore » in turn made of atoms, which are themselves made of electrons and atomic nuclei. Furthermore, the nucleus consists of protons and neutrons, and these nucleons are composed of quarks.« less

Direct observation of hierarchical nucleation of martensite and size-dependent superelasticity in shape memory alloys.

PubMed

Liu, Lifeng; Ding, Xiangdong; Li, Ju; Lookman, Turab; Sun, Jun

2014-02-21

Martensitic transformation usually creates hierarchical internal structures beyond mere change of the atomic crystal structure. Multi-stage nucleation is thus required, where nucleation (level-1) of the underlying atomic crystal lattice does not have to be immediately followed by the nucleation of higher-order superstructures (level-2 and above), such as polysynthetic laths. Using in situ transmission electron microscopy (TEM), we directly observe the nucleation of the level-2 superstructure in a Cu-Al-Ni single crystal under compression, with critical super-nuclei size L2c around 500 nm. When the sample size D decreases below L2c, the superelasticity behavior changes from a flat stress plateau to a continuously rising stress-strain curve. Such size dependence definitely would impact the application of shape memory alloys in miniaturized MEMS/NEMS devices.

The electron screening puzzle and nuclear clustering

DOE PAGES

Spitaleri, C.; Bertulani, C. A.; Fortunato, L.; ...

2016-02-12

Accurate measurements of nuclear reactions of astrophysical interest within, or close to, the Gamow peak show evidence of an unexpected effect attributed to the presence of atomic electrons in the target. The experiments need to include an effective "screening" potential to explain the enhancement of the cross sections at the lowest measurable energies. Despite various theoretical studies conducted over the past 20 years and numerous experimental measurements, a theory has not yet been found that can explain the cause of the exceedingly high values of the screening potential needed to explain the data. Furthermore, in this letter we show thatmore » instead of an atomic physics solution of the "electron screening puzzle", the reason for the large screening potential values is in fact due to clusterization effects in nuclear reactions, in particular for reaction involving light nuclei.« less

Origin and propagation of galactic cosmic rays

NASA Technical Reports Server (NTRS)

Cesarsky, Catherine J.; Ormes, Jonathan F.

1987-01-01

The study of systematic trends in elemental abundances is important for unfolding the nuclear and/or atomic effects that should govern the shaping of source abundances and in constraining the parameters of cosmic ray acceleration models. In principle, much can be learned about the large-scale distributions of cosmic rays in the galaxy from all-sky gamma ray surveys such as COS-B and SAS-2. Because of the uncertainties in the matter distribution which come from the inability to measure the abundance of molecular hydrogen, the results are somewhat controversial. The leaky-box model accounts for a surprising amount of the data on heavy nuclei. However, a growing body of data indicates that the simple picture may have to be abandoned in favor of more complex models which contain additional parameters. Future experiments on the Spacelab and space station will hopefully be made of the spectra of individual nuclei at high energy. Antiprotons must be studied in the background free environment above the atmosphere with much higher reliability and presion to obtain spectral information.

Beta-spectrum shapes of forbidden β decays

NASA Astrophysics Data System (ADS)

Kostensalo, Joel; Suhonen, Jouni

2018-03-01

The neutrinoless ββ decay of atomic nuclei continues to attract fervent interest due to its potential to confirm the possible Majorana nature of the neutrino, and thus the nonconservation of the lepton number. At the same time, the direct dark matter experiments are looking for weakly interacting massive particles (WIMPs) through their scattering on nuclei. The neutrino-oscillation experiments on reactor antineutrinos base their analyses on speculations of β-spectrum shapes of nuclear decays, thus leading to the notorious “reactor antineutrino anomaly.” In all these experimental efforts, one encounters the problem of β-spectrum shapes of forbidden β decays, either as unwanted backgrounds or unknown components in the analyses of data. In this work, the problem of spectrum shapes is discussed and illustrated with a set of selected examples. The relation of the β-spectrum shapes to the problem of the effective value of the weak axial-vector coupling strength gA and the enhancement of the axial-charge matrix element is also pointed out.

Quantum nature of protons in water probed by scanning tunneling microscopy and spectroscopy

NASA Astrophysics Data System (ADS)

Guo, Jing; Lü, Jing-Tao; Feng, Yexin; Chen, Ji; Peng, Jinbo; Lin, Zeren; Meng, Xiangzhi; Wang, Zhichang; Li, Xin-Zheng; Wang, En-Ge; Jiang, Ying; Jing-Tao Lü Team; Xin-Zheng Li Team

The complexity of hydrogen-bonding interaction largely arises from the quantum nature of light hydrogen nuclei, which has remained elusive for decades. Here we report the direct assessment of nuclear quantum effects on the strength of a single hydrogen bond formed at a water-salt interface, using tip-enhanced inelastic electron tunneling spectroscopy (IETS) based on a low-temperature scanning tunneling microscope (STM). The IETS signals are resonantly enhanced by gating the frontier orbitals of water via a chlorine-terminated STM tip, such that the hydrogen-bonding strength can be determined with unprecedentedly high accuracy from the redshift in the O-H stretching frequency of water. Isotopic substitution experiments combined with quantum simulations reveal that the anharmonic quantum fluctuations of hydrogen nuclei weaken the weak hydrogen bonds and strengthen the relatively strong ones. However, this trend can be completely reversed when the hydrogen bond is strongly coupled to the polar atomic sites of the surface.

Measurement of Recoil Losses and Ranges for Spallation Products Produced in Proton Interactions with Al, Si, Mg at 200 and 500 MeV

NASA Technical Reports Server (NTRS)

Sisterson, J. M.

2005-01-01

Cosmic rays interact with extraterrestrial materials to produce a variety of spallation products. If these cosmogenic nuclides are produced within an inclusion in such material, then an important consideration is the loss of the product nuclei, which recoil out of the inclusion. Of course, at the same time, some atoms of the product nuclei under study may be knocked into the inclusion from the surrounding material, which is likely to have a different composition to that of the inclusion [1]. For example, Ne-21 would be produced in presolar grains, such as SiC, when irradiated in interstellar space. However, to calculate a presolar age, one needs to know how much 21Ne is retained in the grain. For small grains, the recoil losses might be large [2, 3] To study this effect under laboratory conditions, recoil measurements were made using protons with energies from 66 - 1600 MeV on Si, Al and Ba targets [3, 4, 5].

Nuclear Dependence of the Transverse-Single-Spin Asymmetry for Forward Neutron Production in Polarized p +A Collisions at √{sN N}=200 GeV

NASA Astrophysics Data System (ADS)

Aidala, C.; Akiba, Y.; Alfred, M.; Andrieux, V.; Aoki, K.; Apadula, N.; Asano, H.; Ayuso, C.; Azmoun, B.; Babintsev, V.; Bagoly, A.; Bandara, N. S.; Barish, K. N.; Bathe, S.; Bazilevsky, A.; Beaumier, M.; Belmont, R.; Berdnikov, A.; Berdnikov, Y.; Blau, D. S.; Boer, M.; Bok, J. S.; Brooks, M. L.; Bryslawskyj, J.; Bumazhnov, V.; Butler, C.; Campbell, S.; Canoa Roman, V.; Cervantes, R.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choi, J. B.; Citron, Z.; Connors, M.; Cronin, N.; Csanád, M.; Csörgő, T.; Danley, T. W.; Daugherity, M. S.; David, G.; Deblasio, K.; Dehmelt, K.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Dion, A.; Dixit, D.; Do, J. H.; Drees, A.; Drees, K. A.; Dumancic, M.; Durham, J. M.; Durum, A.; Elder, T.; Enokizono, A.; En'yo, H.; Esumi, S.; Fadem, B.; Fan, W.; Feege, N.; Fields, D. E.; Finger, M.; Finger, M.; Fokin, S. L.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fukuda, Y.; Gal, C.; Gallus, P.; Garg, P.; Ge, H.; Giordano, F.; Goto, Y.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gunji, T.; Guragain, H.; Hachiya, T.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Hamilton, H. F.; Han, S. Y.; Hanks, J.; Hasegawa, S.; Haseler, T. O. S.; He, X.; Hemmick, T. K.; Hill, J. C.; Hill, K.; Hollis, R. S.; Homma, K.; Hong, B.; Hoshino, T.; Hotvedt, N.; Huang, J.; Huang, S.; Imai, K.; Imrek, J.; Inaba, M.; Iordanova, A.; Isenhower, D.; Ito, Y.; Ivanishchev, D.; Jacak, B. V.; Jezghani, M.; Ji, Z.; Jiang, X.; Johnson, B. M.; Jorjadze, V.; Jouan, D.; Jumper, D. S.; Kang, J. H.; Kapukchyan, D.; Karthas, S.; Kawall, D.; Kazantsev, A. V.; Khachatryan, V.; Khanzadeev, A.; Kim, C.; Kim, D. J.; Kim, E.-J.; Kim, M.; Kim, M. H.; Kincses, D.; Kistenev, E.; Klatsky, J.; Kline, P.; Koblesky, T.; Kotov, D.; Kudo, S.; Kurita, K.; Kwon, Y.; Lajoie, J. G.; Lallow, E. O.; Lebedev, A.; Lee, S.; Leitch, M. J.; Leung, Y. H.; Lewis, N. A.; Li, X.; Lim, S. H.; Liu, L. D.; Liu, M. X.; Loggins, V.-R.; Lökös, S.; Lovasz, K.; Lynch, D.; Majoros, T.; Makdisi, Y. I.; Makek, M.; Malaev, M.; Manko, V. I.; Mannel, E.; Masuda, H.; McCumber, M.; McGaughey, P. L.; McGlinchey, D.; McKinney, C.; Mendoza, M.; Metzger, W. J.; Mignerey, A. C.; Mihalik, D. E.; Milov, A.; Mishra, D. K.; Mitchell, J. T.; Mitsuka, G.; Miyasaka, S.; Mizuno, S.; Montuenga, P.; Moon, T.; Morrison, D. P.; Morrow, S. I. M.; Murakami, T.; Murata, J.; Nagai, K.; Nagashima, K.; Nagashima, T.; Nagle, J. L.; Nagy, M. I.; Nakagawa, I.; Nakagomi, H.; Nakano, K.; Nattrass, C.; Niida, T.; Nouicer, R.; Novák, T.; Novitzky, N.; Novotny, R.; Nyanin, A. S.; O'Brien, E.; Ogilvie, C. A.; Orjuela Koop, J. D.; Osborn, J. D.; Oskarsson, A.; Ottino, G. J.; Ozawa, K.; Pantuev, V.; Papavassiliou, V.; Park, J. S.; Park, S.; Pate, S. F.; Patel, M.; Peng, W.; Perepelitsa, D. V.; Perera, G. D. N.; Peressounko, D. Yu.; Perezlara, C. E.; Perry, J.; Petti, R.; Phipps, M.; Pinkenburg, C.; Pisani, R. P.; Pun, A.; Purschke, M. L.; Radzevich, P. V.; Read, K. F.; Reynolds, D.; Riabov, V.; Riabov, Y.; Richford, D.; Rinn, T.; Rolnick, S. D.; Rosati, M.; Rowan, Z.; Runchey, J.; Safonov, A. S.; Sakaguchi, T.; Sako, H.; Samsonov, V.; Sarsour, M.; Sato, K.; Sato, S.; Schaefer, B.; Schmoll, B. K.; Sedgwick, K.; Seidl, R.; Sen, A.; Seto, R.; Sexton, A.; Sharma, D.; Shein, I.; Shibata, T.-A.; Shigaki, K.; Shimomura, M.; Shioya, T.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Singh, B. K.; Singh, C. P.; Singh, V.; Skoby, M. J.; Slunečka, M.; Smith, K. L.; Snowball, M.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Stankus, P. W.; Stoll, S. P.; Sugitate, T.; Sukhanov, A.; Sumita, T.; Sun, J.; Syed, S.; Sziklai, J.; Takeda, A.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tarnai, G.; Tieulent, R.; Timilsina, A.; Todoroki, T.; Tomášek, M.; Towell, C. L.; Towell, R. S.; Tserruya, I.; Ueda, Y.; Ujvari, B.; van Hecke, H. W.; Vazquez-Carson, S.; Velkovska, J.; Virius, M.; Vrba, V.; Vukman, N.; Wang, X. R.; Wang, Z.; Watanabe, Y.; Watanabe, Y. S.; Wong, C. P.; Woody, C. L.; Xu, C.; Xu, Q.; Xue, L.; Yalcin, S.; Yamaguchi, Y. L.; Yamamoto, H.; Yanovich, A.; Yin, P.; Yoo, J. H.; Yoon, I.; Yu, H.; Yushmanov, I. E.; Zajc, W. A.; Zelenski, A.; Zharko, S.; Zou, L.; Phenix Collaboration

2018-01-01

During 2015, the Relativistic Heavy Ion Collider (RHIC) provided collisions of transversely polarized protons with Au and Al nuclei for the first time, enabling the exploration of transverse-single-spin asymmetries with heavy nuclei. Large single-spin asymmetries in very forward neutron production have been previously observed in transversely polarized p +p collisions at RHIC, and the existing theoretical framework that was successful in describing the single-spin asymmetry in p +p collisions predicts only a moderate atomic-mass-number (A ) dependence. In contrast, the asymmetries observed at RHIC in p +A collisions showed a surprisingly strong A dependence in inclusive forward neutron production. The observed asymmetry in p +Al collisions is much smaller, while the asymmetry in p +Au collisions is a factor of 3 larger in absolute value and of opposite sign. The interplay of different neutron production mechanisms is discussed as a possible explanation of the observed A dependence.

Nuclear Dependence of the Transverse-Single-Spin Asymmetry for Forward Neutron Production in Polarized p+A Collisions at sqrt[s_{NN}]=200  GeV.

PubMed

Aidala, C; Akiba, Y; Alfred, M; Andrieux, V; Aoki, K; Apadula, N; Asano, H; Ayuso, C; Azmoun, B; Babintsev, V; Bagoly, A; Bandara, N S; Barish, K N; Bathe, S; Bazilevsky, A; Beaumier, M; Belmont, R; Berdnikov, A; Berdnikov, Y; Blau, D S; Boer, M; Bok, J S; Brooks, M L; Bryslawskyj, J; Bumazhnov, V; Butler, C; Campbell, S; Canoa Roman, V; Cervantes, R; Chi, C Y; Chiu, M; Choi, I J; Choi, J B; Citron, Z; Connors, M; Cronin, N; Csanád, M; Csörgő, T; Danley, T W; Daugherity, M S; David, G; DeBlasio, K; Dehmelt, K; Denisov, A; Deshpande, A; Desmond, E J; Dion, A; Dixit, D; Do, J H; Drees, A; Drees, K A; Dumancic, M; Durham, J M; Durum, A; Elder, T; Enokizono, A; En'yo, H; Esumi, S; Fadem, B; Fan, W; Feege, N; Fields, D E; Finger, M; Finger, M; Fokin, S L; Frantz, J E; Franz, A; Frawley, A D; Fukuda, Y; Gal, C; Gallus, P; Garg, P; Ge, H; Giordano, F; Goto, Y; Grau, N; Greene, S V; Grosse Perdekamp, M; Gunji, T; Guragain, H; Hachiya, T; Haggerty, J S; Hahn, K I; Hamagaki, H; Hamilton, H F; Han, S Y; Hanks, J; Hasegawa, S; Haseler, T O S; He, X; Hemmick, T K; Hill, J C; Hill, K; Hollis, R S; Homma, K; Hong, B; Hoshino, T; Hotvedt, N; Huang, J; Huang, S; Imai, K; Imrek, J; Inaba, M; Iordanova, A; Isenhower, D; Ito, Y; Ivanishchev, D; Jacak, B V; Jezghani, M; Ji, Z; Jiang, X; Johnson, B M; Jorjadze, V; Jouan, D; Jumper, D S; Kang, J H; Kapukchyan, D; Karthas, S; Kawall, D; Kazantsev, A V; Khachatryan, V; Khanzadeev, A; Kim, C; Kim, D J; Kim, E-J; Kim, M; Kim, M H; Kincses, D; Kistenev, E; Klatsky, J; Kline, P; Koblesky, T; Kotov, D; Kudo, S; Kurita, K; Kwon, Y; Lajoie, J G; Lallow, E O; Lebedev, A; Lee, S; Leitch, M J; Leung, Y H; Lewis, N A; Li, X; Lim, S H; Liu, L D; Liu, M X; Loggins, V-R; Lökös, S; Lovasz, K; Lynch, D; Majoros, T; Makdisi, Y I; Makek, M; Malaev, M; Manko, V I; Mannel, E; Masuda, H; McCumber, M; McGaughey, P L; McGlinchey, D; McKinney, C; Mendoza, M; Metzger, W J; Mignerey, A C; Mihalik, D E; Milov, A; Mishra, D K; Mitchell, J T; Mitsuka, G; Miyasaka, S; Mizuno, S; Montuenga, P; Moon, T; Morrison, D P; Morrow, S I M; Murakami, T; Murata, J; Nagai, K; Nagashima, K; Nagashima, T; Nagle, J L; Nagy, M I; Nakagawa, I; Nakagomi, H; Nakano, K; Nattrass, C; Niida, T; Nouicer, R; Novák, T; Novitzky, N; Novotny, R; Nyanin, A S; O'Brien, E; Ogilvie, C A; Orjuela Koop, J D; Osborn, J D; Oskarsson, A; Ottino, G J; Ozawa, K; Pantuev, V; Papavassiliou, V; Park, J S; Park, S; Pate, S F; Patel, M; Peng, W; Perepelitsa, D V; Perera, G D N; Peressounko, D Yu; PerezLara, C E; Perry, J; Petti, R; Phipps, M; Pinkenburg, C; Pisani, R P; Pun, A; Purschke, M L; Radzevich, P V; Read, K F; Reynolds, D; Riabov, V; Riabov, Y; Richford, D; Rinn, T; Rolnick, S D; Rosati, M; Rowan, Z; Runchey, J; Safonov, A S; Sakaguchi, T; Sako, H; Samsonov, V; Sarsour, M; Sato, K; Sato, S; Schaefer, B; Schmoll, B K; Sedgwick, K; Seidl, R; Sen, A; Seto, R; Sexton, A; Sharma, D; Shein, I; Shibata, T-A; Shigaki, K; Shimomura, M; Shioya, T; Shukla, P; Sickles, A; Silva, C L; Silvermyr, D; Singh, B K; Singh, C P; Singh, V; Skoby, M J; Slunečka, M; Smith, K L; Snowball, M; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Stankus, P W; Stoll, S P; Sugitate, T; Sukhanov, A; Sumita, T; Sun, J; Syed, S; Sziklai, J; Takeda, A; Tanida, K; Tannenbaum, M J; Tarafdar, S; Taranenko, A; Tarnai, G; Tieulent, R; Timilsina, A; Todoroki, T; Tomášek, M; Towell, C L; Towell, R S; Tserruya, I; Ueda, Y; Ujvari, B; van Hecke, H W; Vazquez-Carson, S; Velkovska, J; Virius, M; Vrba, V; Vukman, N; Wang, X R; Wang, Z; Watanabe, Y; Watanabe, Y S; Wong, C P; Woody, C L; Xu, C; Xu, Q; Xue, L; Yalcin, S; Yamaguchi, Y L; Yamamoto, H; Yanovich, A; Yin, P; Yoo, J H; Yoon, I; Yu, H; Yushmanov, I E; Zajc, W A; Zelenski, A; Zharko, S; Zou, L

2018-01-12

During 2015, the Relativistic Heavy Ion Collider (RHIC) provided collisions of transversely polarized protons with Au and Al nuclei for the first time, enabling the exploration of transverse-single-spin asymmetries with heavy nuclei. Large single-spin asymmetries in very forward neutron production have been previously observed in transversely polarized p+p collisions at RHIC, and the existing theoretical framework that was successful in describing the single-spin asymmetry in p+p collisions predicts only a moderate atomic-mass-number (A) dependence. In contrast, the asymmetries observed at RHIC in p+A collisions showed a surprisingly strong A dependence in inclusive forward neutron production. The observed asymmetry in p+Al collisions is much smaller, while the asymmetry in p+Au collisions is a factor of 3 larger in absolute value and of opposite sign. The interplay of different neutron production mechanisms is discussed as a possible explanation of the observed A dependence.

A rare-earth-magnet ion trap for confining low-Z, bare nuclei

NASA Astrophysics Data System (ADS)

Brewer, Samuel M.; Tan, Joseph N.

2009-05-01

Simplifications in the theory for Rydberg states of hydrogenlike ions allow a substantial improvement in the accuracy of predicted levels, which can yield information on the values of fundamental constants and test theory if they can be compared with precision frequency measurements.[1] We consider the trapping of bare nuclei (fully-stripped) to be used in making Rydberg states of one-electron ions with atomic number 1< Z < 11. Numerical simulation is used here to study ion confinement in a compact, Penning-style ion trap consisting of electrodes integrated with rare-earth permanent magnets, and to model the capture of charge-state-selected ions extracted from an electron beam ion trap (EBIT). An experimental apparatus adapted to the NIST EBIT will also be discussed. Reference: [1] U.D. Jentschura, P.J. Mohr, J.N. Tan, and B.J. Wundt, ``Fundamental constants and tests of theory in Rydberg states of hydrogenlike ions,'' Phys. Rev. Lett. 100, 160404 (2008).