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1.
The photoionization cross sections for the 4p shell of ions of the Kr isoelectronic sequence Rb+, Sr2+, and Y3+ are calculated. The configuration interaction theory and the perturbation theory are used to describe the many-electron effects. The relativistic effects are taken into account in the Pauli-Fock approximation. The calculated resonance structure of photoionization cross sections for the 4p shell in the region below the 4s threshold associated with the autoionization of the 4s-np singly excited states and the 4p4p-nln′l′ doubly excited states reproduces the results of recent measurements of total photoabsorption cross sections for the Rb+, Sr2+, and Y3+ ions. It is found that, as the nuclear charge in the isoelectronic sequence increases, the ratio between the direct and correlation parts of amplitudes of the 4s-(n/?)p transition changes and, as the consequence, the minimum of the photoionization cross section of the 4s shell shifts from the continuous spectrum to the region of states of discrete spectrum. This accounts for the strong changes in the shape of the 4s-np resonances in the photoionization cross sections for the 4p shell of Rb+, Sr2+, and Y3+, as well as the distinction between the shapes of the 4s-6p 1/2 mirror resonance in the partial 4p 1/2 and 4p 3/2 photoionization cross sections for the Y3+ ion which do not suppress each other in the total photoionization cross section, as is the case for similar resonances in Rb+ and Sr2+.  相似文献   

2.
The spectra of ruthenium and rhodium excited in a low-inductive vacuum spark have been obtained using a vacuum grazing-incidence spectrograph with a grating of 3600 lines/mm 3 m in radius in the range of 180–350 Å. The bidium-like spectra of Ru VIII and Rh IX were analyzed. Ten spectral lines of the 4p 64d-4p 54d 2 transitions are identified and six energy levels in the 4p 54d 2 configuration with an excited internal electron were found for each ion for the first time.  相似文献   

3.
Let G n ? Diff+(S 1) be the stabilizer of n given points of S 1. How much information do we lose if we restrict a positive energy representation \(U^c_h\) associated to an admissible pair (c, h) of the central charge and lowest energy, to the subgroup G n ? The question, and a part of the answer originate in chiral conformal QFT. The value of c can be easily “recovered” from such a restriction; the hard question concerns the value of h. If c ≤ 1, then there is no loss of information, and accordingly, all of these restrictions are irreducible. In this work it is shown that \(U^c_{h}|_{G_n}\) is always irreducible for n =  1 and, if h =  0, it is irreducible at least up to n ≤  3. Moreover, an example is given for c >  2 and certain values of \(h \neq \tilde{h}\) such that \(U^c_{h}|_{G_1}\simeq U^c_{\tilde{h}}|_{G_1}\) . It is also concluded that for these values \(U^c_{h}|_{G_n}\) cannot be irreducible for n ≥  2. For further values of c, h and n, the question is left open. Nevertheless, the example already shows that, on the circle, there are conformal QFT models in which local and global intertwiners are not equivalent.  相似文献   

4.
The effect of selfabsorption in Mössbauer sources is studied in detail. Spectra were measured using an old 57 C o/R h source of 74M B q activity with an original activity of ca. 3.7G B q and a 0.15G B q 57 C o/α ? F e source magnetized by an in-plane magnetic field of 0.2 T. The 57 C o/α ? F e source of a thickness of 25 μ was used both from the active and the inactive side giving cause to very different selfabsorption effects. The absorber was a single crystal of ferrous ammonium sulphate hexahydrate (FAS). Its absorption properties were taken over from a detailed study (Bull et al., Hyperfine Interact. 94(1–3), 1; Spiering et al. 2). FAS (space group P21/c) crystallizes as flat plates containing the (\(\overline {2}\)01) plane. The γ-direction was orthogonal to the crystal plate. The 57 C o atoms of the 57 C o/R h source were assumed to be homogeneously distributed over a 6μ thick Rh foil and to follow a one dimensional diffusion profile in the 25 μ Fe-foil. The diffusion length was fitted to 10 μ. The theory follows the Blume-Kistner equations for forward scattering (Blume and Kistner, Phys. Rev. 171, 417, 3) by integrating over the source sampled up to 128 layers.  相似文献   

5.
The change in the neutron single-particle structure of (1f?2p)-shell magic nuclei near the Fermi energy with an increase in the number of protons in the 1f 7/2 subshell from 0 for 48Ca to 8 for 56Ni has been investigated. Good agreement of the experimental and estimated values of the single-particle energies E nlj of the bound states of neutrons in these nuclei with the results of calculations within the dispersive optical model is obtained.  相似文献   

6.
Differential cross sections and polarization observables for the elastic and inelastic scattering of 800-MeV protons on 16O and 20Ne nuclei are calculated on the basis of the theory of multiple diffractive scattering and the α-cluster model involving dispersion. The single-particle nucleon-density distributions obtained within the α-cluster model involving dispersion are used in the calculations. The differential cross sections and polarization calculated for elastic and inelastic p16O and p20Ne scattering are compatible with available experimental data. The spin-rotation functions calculated for elastic p16O and p20Ne scattering within the independent-nucleon model differ qualitatively from their counterparts calculated within the α-cluster model involving dispersion.  相似文献   

7.
The photoionization cross sections of the 4p shell and the 4s main level and 4p 4(3 P) 5s 4 P 5/2, 3/2 satellite subvalence levels of KrII have been calculated in the 4s-near-threshold range of excitation energies from 28.48 to 28.70 eV. The calculation takes into account the core relaxation by the methods of the theory of non-orthogonal orbitals, the interaction between resonant states through autoionization channels by solving the complex secular equation, and the interaction between the channels of the continuous spectrum in all orders of the perturbation theory by the K-matrix method. Good quantitative agreement between the energy-integrated theoretical and experimental photoionization cross sections for the satellite levels has been obtained for the first time. It is shown that only simultaneous consideration of the above-mentioned effects leads to such agreement. The resonant structure of the photoionization cross sections in this excitation energy range is related to the autoionization decay of the 4p 45s(4 P 1/2)np and 4p 45s(2 P 3/2)np Rydberg series. The specificity of this process is that both series manifest themselves not independently but owing to their strong electrostatic interaction with the prominent 4p 4(1 D)5s 2 D 5/2 6p 3/2 resonance, which lies in this excitation energy range.  相似文献   

8.
Isomeric ratios of 179Hf m2,g yields in the (γ, n) reaction and the cross section for the 179Hf m2 population in the (α, p) reaction are measured for the first time at the end-point energies of 15.1 and 17.5 MeV for bremsstrahlung photons and 26 MeV for alpha particles. The results are σ = (1.1 ± 0.11) × 10?27 cm2 for the 176Lu(α, p)179Hf m2 reaction and Y m2/Y g = (6.1 ± 0.3) × 10?6 and (3.7 ± 0.2) × 10?6 for the 180Hf(γ, n)179Hf m22 reaction at Е ep =15.1 and 17.5 MeV, respectively. The experimental data on the relative 179Hf m2 yield indicate a single-humped shape of the excitation function for the 180Hf(γ, n)179Hf m2 reaction. Simulation is performed using the TALYS-1.4 and EMPIRE-3.2 codes.  相似文献   

9.
High-resolution laser spectroscopy measurements of optical hyperfine splitting on the 151, 152, 153Eu isotopes were performed on the atomic transition 4f 76s 2 8 S 7/2 → 4f 76s6p 6 P 5/2 at λ ≈ 564.58 nm. Values of the nuclear magnetic dipole and electric quadrupole moments are obtained from the measured hyperfine splitting and the magnetic hyperfine anomalies in the isotope pairs 151, 152Eu and 152, 153Eu are deduced. The absolute values of the hyperfine anomaly in both cases are unusually large: 5 (1)%. The possible sources causing these anomalies are discussed.  相似文献   

10.
A theoretical model has been developed to calculate the emissivity of low densityxenon plasmas (from Xe8+ to Xe12+) by employing a detailed lineaccounting formalism. A complete set of atomic datasuch as transition probabilities for electric (magnetic) dipoleand quadruple E1, E2, M1 and M2 and electron impact excitationcollision strength, which is accurate to fine-structure level,was calculated using a full configuration interaction formalismand was used to solve the rate equation which determines thepopulation of different levels. Detailed results are given forpure Xe10+ ion, which is essential for extreme-ultravioletemission at 13.5 nm, and for low density plasmas (the electron densitywas taken to be 1012 cm-3) at temperatures of 30, 45, 55, 65and 75 eV. The fraction of different ionization stages was obtained by acompletely coupled rate equation from neutral atom to Xe20+ by usinga detailed configuration accounting method. The results show that theemissivity of the dipole forbidden lines of transition array4s 24p 64d 75s \(\rightarrow\) 4s 24p 64d 8 of Xe10+is very sensitive to the temperature, which should be a useful tool todiagnose the temperature in EBIT plasmas.  相似文献   

11.
High spin states in 127Xe have been investigated via 9Be induced fusion-evaporation reaction at 48 MeV. Spin and parity of excited states up to \( \sim \frac {47}{2} \hbar \) have been confirmed from angular correlation and linear polarization results. Rotational alignment of the second pair of h 11/2 neutrons has been observed at \(\hbar \omega \sim \) 0.44 MeV; beyond that, the band is associated with ν[h 11/2]3 configuration. The alignment phenomena has been discussed in comparison with the neighboring 125,129Xe.  相似文献   

12.
The absorption, luminescence, and excitation spectra of CaF2, SrF2, and BaF2 crystals with EuF3 or YbF3 impurity have been investigated in the range 1–12 eV. In all cases, strong wide absorption bands (denoted as CT1) were observed at energies below the 4f n -4f n ? 15d absorption threshold of impurity ions. Weaker absorption bands (denoted as CT2) with energies 1.5–2 eV lower than those of the CT1 bands have been found in the spectra of CaF2 and SrF2 crystals with EuF3 or YbF3 impurities. The fine structure of the luminescence spectra of CaF2 crystals with EuF3 impurities has been investigated under excitation in the CT bands. Under excitation in the CT1 band, several Eu centers were observed in the following luminescence spectra: C 4v , O h , and R aggregates. Excitation in the CT2 bands revealed luminescence of only C 4v defects.  相似文献   

13.
Basic methods for determining cross sections for photoneutron partial reactions are examined. They are obtained directly in experiments with quasimonoeneregetic annihilation photons or from the cross section for the (γ, xn) = (γ, 1n) + 2(γ, 2n) + 3(γ, 3n) +... neutron-yield reaction in experiments with bremsstrahlung photons by introducing corrections based on statistical nuclear-reaction theory. The difference in the conditions of these experiments, which leads to discrepancies between their results because of sizable systematic errors, is analyzed. Physical criteria are used to study the reliability of data on the photodisintegration of 133Cs, 138Ba, and 209Bi nuclei. The cross sections for partial and total reactions satisfying the reliability criteria are evaluated within the experimental–theoretical method (σeval(γ, in) = Fitheor × σexpt(γ, xn)) on the basis of the experimental cross sections σexpt(γ, xn) and the results of the calculations within the combined model of photonuclear reactions.  相似文献   

14.
The formation of cumulative nuclei of 4He in 16Op collisions at a momentum of 3.25 GeV/c per nucleon was investigated for the first time under conditions of 4π acceptance. The slope parameter of the invariant cross sections for the formation of cumulative nuclei of 4He was determined, and new data on the correlations between the yield of these cumulative nuclei and the yield of charged particles and fragments in 16Op interactions were obtained.  相似文献   

15.
The results of studies of the absorption spectra of nickel orthoborate Ni3(BO3)2 in the range of electronic dd-transitions are reported. The obtained data are analyzed in the framework of the crystal field theory. The Ni2+ ions are located in two crystallographically nonequivalent positions 2a and 4f with point symmetry groups C2h and C2, respectively, surrounded by six oxygen ions forming deformed octahedra. The absorption spectra exhibit three intense bands corresponding to spin-resolved transitions from the ground state of nickel ion 3A2g (3F) to the sublevels of the 3T2g (3F), 3T1g (3F) and 3T1g (3P) triplets split by the spinorbit interaction and the rhombic component of the crystal field. At temperatures below 100 K, the spectra exhibit a thin structure, in which phonon-free lines can be distinguished. Comparison of the calculated frequencies of the zero-phonon transitions with the experimental data allows estimating parameters of the crystal field acting on the nickel ions in the 2a- and 4f-positions, as well as the parameters of electrostatic interaction between the 3d electrons and spin-orbit interaction constants.  相似文献   

16.
Correlations of secondary protons in 4Hep interactions are investigated in an exclusive experiment with the aid of a 2-m liquid-hydrogen bubble chamber exposed to an alpha-particle beam of momentum 5 GeV/c the kinetic energy of primary protons in the rest frame of the nucleus is Tp=620 MeV). By using data obtained in 4π geometry for six basic channels of 4Hep interaction that lead to the production of two protons, the total correlation function for the pp system is determined, along with two-proton correlation functions for individual channels. Experimental results are compared with the predictions of the modified Lednicky-Lyuboshitz model. The value of R=1.6±0.3 fm is obtained for the root-meansquare spacetime radius of pp emission in 4Hep interactions. The dependence of the correlation function on the total momentum of two emitted protons and on the momentum-transfer direction is investigated.  相似文献   

17.
We provide a series of arguments which support the idea that the peak seen in the \( \gamma\) p \( \rightarrow\) K + \( \Lambda\) reaction around 1920MeV should correspond to the recently predicted state of J P = 1/2+ as a bound state of K \( \bar{{K}}\) N with a mixture of a 0(980)N and f 0(980)N components. At the same time we propose polarization experiments in that reaction as a further test of the prediction, as well as a study of the total cross-section for \( \gamma\) p \( \rightarrow\) K + K - p at energies close to threshold and of dσ/dM inv for invariant masses close to the two-kaon threshold.  相似文献   

18.
G. E. Volovik 《JETP Letters》2018,107(5):324-326
The time reversal symmetric polar phase of the spin-triplet superfluid 3He has two types of Dirac nodal lines. In addition to the Dirac loop in the spectrum of the fermionic Bogoliubov quasiparticles in the momentum space (p x , p y , p z ), the spectrum of bosons (magnons) has Dirac loop in the 3D space of parameters—the components of magnetic field (H x ,H y ,H z ). The bosonic Dirac system lives on the border between the type-I and type-II.  相似文献   

19.
Coriolis interaction between levels of two rotational bands in 172Yb with K π = 2+ and 3+ and in 168Er between levels with K π = 0?, 1?, and 2? is studied. The values of the interaction parameters are obtained. The mutual influence of two bands in 162Dy with ΔK = 2, K i π = 0 2 + and 2 1 + due to Coriolis interaction is demonstrated.  相似文献   

20.
Proton-neutron correlations in 4Hep interactions are studied in an exclusive experiment by using a 2-m bubble chamber exposed to a 5-GeV/c beam of α particles (the kinetic energy of the protons in the nucleus rest frame is T p = 620 MeV). Data on the production of pn pairs in 4π geometry for three channels, where it is possible to reconstruct the neutron momentum unambiguously, are used to determine the pn correlation function in 4Hep interactions. The experimental results are compared with the predictions of a modified Lednicky-Lyuboshitz model. The value obtained for the root-mean-square radius of the pn-emission region is R pn = 2.1 ± 0.3 fm. The dependence of the correlation function on the modulus of the total momentum of the emitted nucleon pair and on the direction of the momentum transfer is studied. An indication that the emission of a pn pair proceeds predominantly through the production of a virtual deuteron is obtained.  相似文献   

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