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1.
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. 相似文献
2.
V. M. Azriel’ V. M. Akimov L. I. Kolesnikova L. Yu. Rusin M. B. Sevryuk J. P. Toennies 《Russian Journal of Physical Chemistry B, Focus on Physics》2009,3(6):857-863
By means of quantum mechanical simulation of the reaction F + H2(v = 0; j = 0, 1, 2) → H + HF(v′, j′) on the Stark-Werner ground state potential energy surface at collision energies of 1.84, 2.74, and 3.42 kcal/mol, we have
analyzed interference of the “partial waves” corresponding to different values of the total angular momentum J. As the vibrational quantum number v′ of the HF(v′, j′) product increases, the interference for the HF forward scattering becomes noticeably more constructive. This is probably
the reason for the maximum in the angular distributions of the HF(v′= 3) molecules at small scattering angles that was discovered experimentally by D.M. Neumark, A.M. Wodtke, G.N. Robinson,
C.C. Hayden, and Y.T. Lee, J. Chem. Phys. 82 (7), 3045 (1985) at the same collision energies. We have also determined the intervals of J values most effective for forward scattering of the HF(v′, j′) molecules. 相似文献
3.
W. von Oertzen 《The European Physical Journal A - Hadrons and Nuclei》2006,29(2):133-139
The systematics for binding energies per α-particle in N = Z nuclei, E
Bα/N
α, are studied up to 164Pb. It is shown that, although a geometrical model can be used to explain the systematics for light nuclei, the binding energy
per α-particle exhibits structures which are due to the well-known shells of the mean field of nucleons in nuclei. The overall
dependence of E
Bα/N
α on N
α in N = Z nuclei (for the ground-state masses) can be described in a liquid-drop model of α-particles. Conditions for a phase change
with the formation of an α-particle condensate, a dilute Bose gas in excited compound nuclei are discussed for E
Bα/N
α = 0, at the thresholds. This is achieved when the binding energy per nucleon in nuclei is equal to or smaller than in the
α-cluster. At somewhat smaller excitation energies the appearance of a Bose gas with a closed-shell core (N = Z, e.g. of 40Ca) is proposed within the same concept. The experimental observation of the decay of such condensed α-particle states is
proposed with the coherent emission of several correlated α-particles not described by the Hauser-Feshbach approach for compound-nucleus
decay. This decay will be observed by the emission of unbound resonances in the form of 8Be and 12C * (0+
2) clusters. 相似文献
4.
In this work, we explain our astrophysical motivations for deriving a mass formula based on HFB calculations with a Skyrme
interaction. We give an overview of existing mass formulae and present briefly the last HF+BCS mass formula [1]. The Skyrme
force MSk7 [1] is considered in the study of shell effects at N=82, in the neutron-rich region far from stability, within the HFB and HF+BCS theories, and compared with results obtained
using the forces SkPδ and SkPδρ [2].
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
5.
The binding energy, symmetry energy, pressure, incompressibility, and the velocity of sound are calculated for asymmetric
nuclear matter using Skyrme interaction SkO’. The behavior of these physical quantities is studied for different values of the asymmetry parameter α
τ
, the density ρ, and the temperature T. Good agreement is obtained in comparison with previous theoretical estimates and experimental data.
The text was submitted by the authors in English. 相似文献
6.
S. E. Chigrinov K. K. Gudima A. I. Kievitskaya V. A. Petlitsky 《Hyperfine Interactions》1993,77(1):149-159
In this paper, we present a model of calculation with respect to the interactions of high-energy nuclei with matter. Based
on this model, we obtain results on energy and angular spectra of the n- and π−-particles produced in collisions of deuterium and tritium nuclei at energiesT
d=1 GeV/nucleon with light targets such as Li, Be. We have also estimated the production yields of neutrons and π−-mesons in targets of various radii, as well as mean energies of these these particles. Summarizing, we find that the lithium
target of radiusR=10−12 cm for which the energy cost επ to produce one π−-meson is estimated as 6.7 GeV/π for a d-beam and 5.3 GeV/π for a t-beam is the most preferred pion-production target. 相似文献
7.
Nils Dalarsson 《International Journal of Theoretical Physics》1997,36(5):1209-1225
The kaon coupling constants at hyperon-nucleon vertices and the pion coupling constants at hyperon-hyperon vertices are calculated
in the framework of the constant-cutoff approach to the CHK bound-state model of hyperons, where the postive-parity hyperons
such as Λ, Σ, and ∑*=∑(1385) are theP-wave bound states of an antikaon and theSU(2) Skyrme soliton, while Λ* is theS-wave bound state. Meson coupling constants are defined as matrix elements of the meson-source terms between two single-baryon
states following the method developed for resolving the Yukawa coupling problem in theSU(2) Skyrme soliton model. The magnitudes of the meson coupling constants are found to be close to those obtained using the
complete Skyrme model and the phenomenological values. 相似文献
8.
On the basis of the total cross sections for neutron-proton scattering in the region of laboratory energies below 150 keV,
the value of σ0 = 20.4288(146) b was obtained for the total cross sections for neutron-proton scattering at zero energy. This value is in
very good agreement with the experimental cross sections obtained by Houke and Hurst, but it is at odds with Dilg’s experimental
cross section. By using the value that we found for σ0 and the experimental values of the neutron-proton coherent scattering length f, the deuteron binding energy ɛ
t
, the deuteron effective radius ρ
t
(−ɛ
t
, −ɛ
t
), and the total cross section in the region of energies below 5 MeV, the following values were found in the shape-parameter
approximation for the low-energy parameters of neutron-proton scattering in the spin-triplet and spin-singlet states: a
t
= 5.4114(27) fm, r
0t
= 1.7606(35) fm, v
2t
= 0.157 fm3, a
s
= −23.7154(80) fm, r
0s
= 2.706(67) fm, and v
2s
= 0.491 fm3. 相似文献
9.
Chandu Venugopal 《Pramana》1987,28(2):181-193
A dispersion relation for the near perpendicular propagation of the electromagnetic ion cyclotron wave has been derived in
a fusion plasma that has deuterium as a majority species, hydrogen as a minority species and fully ionized oxygen as an impurity
constituent; all being modelled by loss cone distribution functions. The wave has a frequencyω around the deuterium ion gyrofrequency-ΩD and a wavelength much longer than its Larmor radiusγ
LD(k
⊥
γ
LD<1); the plasma itself being characterized by large ion plasma frequencies (ω
PD
2
>Ω
D
2
). Two modes, a low frequency (LF) and a high frequency (HF) mode of opposite electrical energy can propagate in the plasma;
the instabilities that arise are thus due to an interaction of modes of opposite energies. We find that while hydrogen tends
to destabilize the plasma, the impurity oxygen ions have the reverse effect. Also the plasma is most stable when the ratios
of the perpendicular components of oxygen-to-deuterium and hydrogen-to-deuterium temperatures are kept low. Detailed studies
of the wave propagation characteristics and energy reveal the close resemblance of a loss cone plasma containing oxygen to
a stable Maxwellian plasma in regard to wave stability, propagation and energy. 相似文献
10.
Qiaohuan Cheng Sourabhi Debnath Elizabeth Gregan Hugh J. Byrne 《Applied Physics A: Materials Science & Processing》2011,102(2):309-317
This study establishes a generic fitting approach to assignment of nanotube chiralities based on radial breathing mode frequencies
(ω
RBM) of SWCNTs in as-produced bundles. Four laser lines with energies of 2.62 eV, 2.33 eV, 1.88 eV and 1.58 eV were employed.
The observed RBM frequencies, ω
RBM, were plotted as a function of the possible diameters, d, as identified from the so-called Kataura plot and reported values of the parameters A and B, where ω
RBM=A/d+B, assuming that SWCNTs resonant at the respective laser frequencies dominate the spectrum. The refined values of A and B, obtained by the best fit of a linear regression between ω
RBM and 1/d, were found to vary significantly for different laser frequencies. This variation is interpreted in terms of the differences
in electronic properties of SWCNTs resonant at different frequencies. The assigned nanotubes match well with those identified
in the Kataura plot, falling within a resonant line width of ±0.2 eV of the respective laser lines. 相似文献
11.
We combine the thermal QRPA approach with the Skyrme energy density functional theory (Skyrme–TQRPA) for modelling the process of electron capture on nuclei in supernova environment. For a sample nucleus, 56Fe, the Skyrme–TQRPA approach is applied to analyze thermal effects on the strength function of GT+ transitions which dominate electron capture at E e ≤ 30 MeV. Several Skyrme interactions are used in order to verify the sensitivity of the obtained results to the Skyrme force parameters. Finite-temperature cross sections are calculated and the results are comparedwith those of the other model calculations. 相似文献
12.
13.
S. V. Tolokonnikov I. N. Borzov Yu. S. Lutostansky E. E. Saperstein 《Physics of Atomic Nuclei》2016,79(1):21-37
The deformation properties of a long lead isotopic chain up to the neutron drip line are analyzed on the basis of the energy density functional (EDF) in the FaNDF0 Fayans form. The question of whether the ground state of neutron-deficient lead isotopes can have a stable deformation is studied in detail. The prediction of this deformation is contained in the results obtained on the basis of the HFB-17 and HFB-27 Skyrme EDF versions and reported on Internet. The present analysis reveals that this is at odds with experimental data on charge radii and magnetic moments of odd lead isotopes. The Fayans EDF version predicts a spherical ground state for all light lead isotopes, but some of them (for example, 180Pb and 184Pb) prove to be very soft—that is, close to the point of a phase transition to a deformed state. Also, the results obtained in our present study are compared with the predictions of some other Skyrme EDF versions, including SKM*, SLy4, SLy6, and UNE1. By and large, their predictions are closer to the results arising upon the application of the Fayans functional. For example, the SLy4 functional predicts, in just the same way as the FaNDF0 functional, a spherical shape for all nuclei of this region. The remaining three Skyrme EDF versions lead to a deformation of some light lead isotopes, but their number is substantially smaller than that in the case of the HFB-17 and HFB-27 functionals. Moreover, the respective deformation energy is substantially lower, which gives grounds to hope for the restoration of a spherical shape upon going beyond the mean-field approximation, which we use here. Also, the deformation properties of neutron-rich lead isotopes are studied up to the neutron drip line. Here, the results obtained with the FaNDF0 functional are compared with the predictions of the HFB-17, HFB-27, SKM*, and SLy4 Skyrme EDF versions. All of the EDF versions considered here predict the existence of a region where neutron-rich lead isotopes undergo deformations, but the size of this region is substantially different for the different functionals being considered. Once again, it is maximal for the HFB-17 and HFB-27 functionals, is substantially narrower for the FaNDF0 functional, and is still narrower for the SKM* and SLy4 functionals. The two-neutron drip line proved to be Adrip2n = 266 for all of the EDF versions considered here, with the exception of SKM*, for which it is shifted to Adrip2n(SKM*) = 272. 相似文献
14.
《Hyperfine Interactions》2001,132(1-4):133-139
For many nuclei beyond the proton drip line in the Z>72, N>82 region, both proton and α emission are energetically allowed. In the case of some proton emitters, there are α-decay chains
emanating from both parent and daughter nuclei. This means that if the mass excess of one member of an α-decay chain is known,
then the mass excesses for all members of both chains can be obtained. In addition, proton separation energies may be derived
for nuclei in the α-decay chain of the proton emitter. The method of time- and space-correlations also allows the identification
of isomeric states in these nuclei. As an example, a large number of mass excesses and proton separation energies for ground
and metastable states have been derived from Q
α and Q
p values obtained from the proton emitters 165,166,167Ir, 171Au, 177Tl, and their daughters.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
15.
G. Mandaglio G. Fazio G. Giardina F. Hanappe M. Manganaro A. I. Muminov A. K. Nasirov C. Saccá 《Physics of Atomic Nuclei》2009,72(10):1639-1650
The measured yield of evaporation residues in reactions with massive nuclei have been well reproduced by using the partial
fusion and quasifission cross sections obtained in the dinuclear-system model. The influence of the orientation angles of
the projectile- and target-nucleus symmetry axes relative to the beam direction on the production of the evaporation residues
is investigated for the 48Ca + 154Sm reaction as a function of the beam energy. At the low beam energies only the orientation angles close to αP = 30° (projectile) and αP = 0°–15° (target) can contribute to the formation of evaporation residues. At large beam energies (about E
c.m. = 140–180 MeV) the collisions at all values of orientation angles αP and α
T
of reactants can contribute to the evaporation residue cross section which ranges between 10–100 mb, while at E
c.m. > 185 MeV the evaporation residue cross section ranges between 0.1–1 mb because the fission barrier for the compound nucleus
decreases by increasing its excitation energy and angular momentum. 相似文献
16.
A combination of the semimicroscopic, exciton, and evaporation models is used to describe photonucleon reactions induced in
medium-mass and heavy nuclei by photons of energy below the mesonproduction threshold. Two mechanisms of the photoexcitation
of nuclei are considered. These are the formation of a giant dipole resonance (GDR) at energies in the range E
γ
≲ 30 MeV and quasideuteron photoabsorption, which is dominant at energies in the region E
γ
≳ 40 MeV. The densities of particle-hole states appearing in the exciton model are calculated on the basis of the Fermi gas
model. Our combined model takes into account the multiparticle emission of preequilibrium particles. The influence of isospin
conservation and collective phenomena on photonucleon emission by giant dipole resonances is considered. The combined model
is used to describe cross sections for photonucleon reactions proceeding on the 40,48Ca, 90Zr, 139La, 142Nd, and 181Ta nuclei, as well as difference (E
γmax = 85–55 MeV) bremsstrahlung photoneutron spectra for the 63Cu, 115In, 118Sn, 181Ta, 207Pb, 209Bi, and 235U nuclei and bremsstrahlung photoproton spectra for the 90Zr nucleus at the energies of E
γmax = 22, 25, and 34 MeV. 相似文献
17.
A large stack of lead-emulsion sandwich detector assembly was flown over Hyderabad, India. High energy gamma rays at the float
altitude were unambiguously identified from the cascades they induced, and their energies reliably determined by improved
methods. From an analysis of 163 gamma rays of energy ≳ 30 GeV, it is found that the differential energy spectrum is represented
by the power lawJ
r
(E)= 129·4E
−2·62±0·12 photons m−2 sr−1sec−1 GeV−1 at an effective atmospheric depth of 14·3 g cm−2; this is the first reliable balloon measurement of atmospheric gamma rays in the energy range 40–1000 GeV. After correcting
for the gamma rays radiated by the primary cosmic ray electrons, the production spectrum of gamma rays, resulting from the
collisions of cosmic ray nuclei with air nuclei, at the top of the atmosphere isP
r
(E, 0)=8·2 × 10−4 E2.60±0.09 photons g−1sr−1sec−1 GeV−1. The atmospheric propagation of the electromagnetic component due to the cascade process is also derived from the gamma ray
production spectrum. 相似文献
18.
The recently developed semiclassical variational Wigner-Kirkwood (VWK) approach is applied to finite nuclei using external potentials and self-consistent mean fields derived from Skyrme interactions and from relativistic mean field theory. VWK consists of the Thomas-Fermi part plus a pure, perturbative ?2 correction. In external potentials, VWK passes through the average of the quantal values of the accumulated level density and total energy as a function of the Fermi energy. However, there is a problem of overbinding when the energy per particle is displayed as a function of the particle number. The situation is analyzed comparing spherical and deformed harmonic oscillator potentials. In the self-consistent case, we show for Skyrme forces that VWK binding energies are very close to those obtained from extended Thomas-Fermi functionals of ?4 order, pointing to the rapid convergence of the VWK theory. This satisfying result, however, does not cure the overbinding problem, i.e., the semiclassical energies show more binding than they should. This feature is more pronounced in the case of Skyrme forces than with the relativistic mean field approach. However, even in the latter case the shell correction energy for e.g., 208Pb turns out to be only ∼−6 MeV what is about a factor two or three off the generally accepted value. As an ad hoc remedy, increasing the kinetic energy by 2.5%, leads to shell correction energies well acceptable throughout the periodic table. The general importance of the present studies for other finite Fermi systems, self-bound or in external potentials, is pointed out. 相似文献
19.
Analytical expressions are derived for the components of the intrinsic frame inverse mass tensor of the Bohr Hamiltonian.
These expressions contain parameters which are determined by the experimental data on the B(E2)’s and the excitation energies of the low-lying collective states. It is shown that the nondiagonal component of the intrinsic
frame mass tensor has a small effect on the collective motion. It is shown also that the values of the B
ββ
, B
γγ
and the rotational mass coefficientB
1 differ in the well-deformed nuclei by factor 3 or more. 相似文献
20.
《Nuclear Physics A》1997,626(3):669-685
Using the self-consistent Hartree-Fock calculation plus RPA with Skyrme interactions, the RPA quadrupole strength function is estimated in the coordinate space, including simulataneously both the isoscalar and the isovector correlation. We discuss the result of the isoscalar, the isovector and the electric quadrupole polarization of the Ca-isotopes from the proton drip line towards the neutron drip line. We study also the comparison of the polarizations in the A = 48 mirror nuclei, 2848Ni20 and 2048Ca28, and the dependence of the polarizations of 828O20 on various Skyrme interactions. 相似文献