Semileptonic decays of the hypernucleus4HΛ

Two-channel type semileptonic decays of the hypernucleus⁴H are considered:⁴H_A ³H+p+^–+ and⁴H³He+n+^–+ . The particle energy spectra are computed taking into account the presence of strong interaction in the final state and the Pauli principle both in the direct and in the charge-exchange decay channels.The importance of the role played by interactions in forming the spectra of particles created in decays, is noted. Characteristic features of energy spectra and angular correlations of particles in the charge-exchange decay channel are discussed. The importance of such effects is noted for the dynamics of multichannel mesonless hypernuclear decays with similar energy release values.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 42–45, July, 1990.     

A-dependence of ΛΛ bond energies in double-Λ hypernuclei

The A-dependence of the bond energy ΔB_ΛΛ of the ΛΛ hypernuclear ground states is calculated in a three-body Λ + Λ + ^A Z model and in the Skyrme-Hartree-Fock approach. Various ΛΛ and Λ-nucleus or ΛN potentials are used and the sensitivity of ΔB_ΛΛ to the interactions is discussed. It is shown that in medium and heavy ΛΛ hypernuclei, ΔB_ΛΛ is a linear function of r _Λ ^{? 3} , where r _Λ is rms radius of the hyperon orbital. It looks unlikely that it will be possible to extract ΛΛ interaction from the double-Λ hypernuclear energies only, the additional information about the Λ- core interaction, in particular, on r _Λ is needed.     

Three-body calculation of Be double-Λ hypernuclei

Energy levels and Λ Λ bond energy of the double- Λ hypernucleus are calculated by considering two- and three-cluster interactions. Interactions between constituent particles are contact interactions for reproducing the low binding energy of nuclei. The effective action is constructed to involve three-body forces. In this paper, we also compare the obtained binding energy result with experimental and other cluster and shell models. The results of all schemes agree very well showing the high accuracy of our method to calculate the other many-body hyperonic nuclei using three-cluster interactions. The experimental values of \(B_{\Lambda {\Lambda }}(^{10}_{\Lambda {\Lambda }}\) Be) = (11.90 ± 0.13) MeV, \(B_{\Lambda {\Lambda }}(^{11}_{\Lambda {\Lambda }}\) Be) = (20.49 ± 1.15) MeV and \(B_{\Lambda {\Lambda }}(^{12}_{\Lambda {\Lambda }}\) Be) = (22.23 ± 1.15) MeV seem to be more compatible with our calculated value of \(B_{\Lambda {\Lambda }}(^{10}_{\Lambda {\Lambda }}\) Be) = 14.04 MeV, \(B_{\Lambda {\Lambda }}(^{11}_{\Lambda {\Lambda }}\) Be) = 19.31 MeV and \(B_{\Lambda {\Lambda }}(^{12}_{\Lambda {\Lambda }}\) Be) = 21.45 MeV in comparison with the other calculated results by Hiyama et al, Gal et al and Guleria et al.     

Binding energy and rates of Σ-hyperon decays of double hypernuclei

The binding energies of double hypernuclei are calculated as a function of mass number. Estimates are made for the width of the -hyperon decay channel of double hypernuclei. Significant suppression of this channel due to -to- conversion is found in heavy hypernuclei.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 70–73, April, 1989.     

利用手征SU(3)夸克模型研究轻超核5ΛHe,4ΛHe和4ΛH的结合能

利用手征SU(3)夸克集团模型，通过共振群方法(RGM)得到了非定域的YN 相互作用势和Λ超子与壳心核的相互作用势,并计算了轻Λ超核5ΛHe,4ΛHe和4ΛH 的结合能. 计算结果表明，手征SU(3)夸克集团模型不仅能较好地描述Λp散射，也能较好地描述轻Λ超核的结合能. 由于利用共振群方法(RGM)直接抽取的非定域YN相互作用势更为准确，因此计算得到的轻Λ超核5ΛHe ,4ΛHe 和4ΛH 的结合能更符合实验数据，同时，也为将来的超核和多夸克体系确定了一套更为精确的模型参数.     

Double-Λ hypernuclei and the nuclear medium effective ΛΛ interaction

We fit the ¹S₀ ΛΛ interaction in the nuclear medium to the masses of the experimentally known double-Λ hypernuclei: _ΛΛ⁶He, _ΛΛ¹⁰Be and _ΛΛ¹³B. We derive this effective interaction from OBE Jülich ΛΛ-type potentials and using both Hartree-Fock and variational approaches. We find that the inclusion of ΛΛ correlations in the variational scheme leads to significant differences and a better understanding of the dynamical features of the system. We investigate the sensitivity of the binding energies and the mesonic decay widths of the above double-Λ hypernuclei to the ωΛΛ coupling and the form factor at the σΛΛ vertex. We also use this effective interaction to predict binding energies and pionic decay widths of heavier double-Λ hypernuclei, not discovered yet. Finally, we discard the existence of ¹S₀ ΛΛ bound states provided the ΛΛ-ΞN coupling can be neglected.     

Structure of A=11 double-Λ hypernuclei studied withthree-body forces

The energy levels and ΛΛ bond energy of the double-Λ hypernucleus ¹¹Be are calculated considering two- and three-nucleon forces. The interactions between the constituent particles are contact interactions that reproduce the low-energy binding energy of the nuclei. Effective action is constructed to involve the three-body forces. In this paper, we compare the binding energy result that is obtained with the experimental and other modern nucleon-nucleon potentials. The results of all the schemes agree very well, showing the high accuracy of our present ability to calculate the many-nucleon bound state with three-body forces. The experimental value of B_{Λ Λ}(_ΛΛ¹¹Be)=20.83 MeV seems to be more compatible with our calculated value of B_ΛΛ(_ΛΛ¹¹Be)=19.31 MeV in comparison with the calculated result of 18.23 MeV by Hiyama et al.     

利用手征SU(3)夸克模型研究轻超核_Λ~5He,_Λ~4He和_Λ~4H的结合能

利用手征SU(3)夸克集团模型,通过共振群方法(RGM)得到非定域的YN相互作用势和Λ超子与壳心核的相互作用势,并用其计算了轻Λ超核5ΛHe,4ΛHe和4ΛH的结合能.计算结果表明,手征SU(3)夸克集团模型不仅能较好地描述Λp散射,也能较好地描述轻Λ超核的结合能.由于利用共振群方法(RGM)直接抽取的非定域YN相互作用势更为准确,因此计算得到的轻Λ超核5ΛHe,4ΛHe和4ΛH的结合能更符合实验数据,同时,这也为将来研究超核和多夸克体系确定了一套更为精确的模型参数.     

Diffraction scattering of Λ 3 H and Λ 6 He hypernuclei on nuclei with allowance for edge diffuseness, the structure of hypernuclei, and multiple-scattering effects

General formulas for the amplitudes of the diffraction scattering of two-and three-cluster loosely bound nuclei on spherical nuclei for an arbitrary dependence of the profile functions on the impact parameter are represented in a form that is convenient for calculations. The differential cross sections for the elastic scattering of _Λ ³ H and _Λ ⁶ He hypernuclei and the total cross sections are obtained with allowance for the diffuseness of the target-nucleus edge, the binding energy of incident hypernuclei, the ranges of nuclear forces between the clusters in the hypernuclei, and multiple (double and triple) scattering. Changes in the behavior of the cross sections in response to a transition from the two-cluster to the three-cluster model of the aforementioned nuclei are revealed.     

利用少体方法计算_Λ~3H,_Λ~4H,_Λ~4He的基态结合能

在手征SU（3）夸克模型和谐振子基下,Y-N（超子-核子）相互作用采用非定域势,N-N相互作用采用高斯型势,根据少体理论研究并计算了轻超核3 H 4 H 4He,,ΛΛΛ的基态结合能,并同实验值做了比较。     

双超核ΛΛ5H,ΛΛ5He,ΛΛ4H,ΛΛ4He的研究

用少体理论方法对双Λ超核ΛΛ5He(ΛΛ5H)及ΛΛ4He(ΛΛ4H)的结合能进行了计算．结果表明,ΛΛ5He(ΛΛ5H)存在稳定的束缚态. 它们的双Λ结合能分别为对的研究的初步结果表明，它存在束缚态但相对于衰变不稳定．至于，结论是它不存在束缚态．     

Quadrupole moments of medium-weight and heavy hypernuclei with the NΛ configurations (N = p and n)

Using the shell model wave functions, we have studied quadrupole moments of medium-weight and heavy hypernuclei, and obtained the shell model values of quadrupole moments of NΛ systems ( N = p and n). With the use of the first-order perturbation theory, we have also estimated the configuration mixing effects on quadrupole moments of these NΛ hypernuclei. We show that the hyperon-induced configuration mixing effects are small and the nucleon-induced configuration mixing effects are large in many cases. Received: 22 February 2000 / Accepted: 2 August 2000     

Relativistic motion of the λ in hypernuclei and phenomenological analysis of its energy

A phenomenological analysis of the ground state binding energy B(A) of a -particle in hypernuclei which is based on the Dirac equation with scalar potential and fourth component of vector potential of rectangular shape is presented.Presented at the symposium Mesons and Light Nuclei, Bechyn, Czechoslovakia. May 27–June 1, 1985.The authors would like to thank Prof. R. Brockmann for pointing out to them the importance of inclusion of the vector boson exchange potential (the same comment was made by Prof. R. Bodmer) and for other useful suggestions. Thanks are also due to the staff of the computing centre of the University of Thessaloniki for their cooperation.     

Variational Calculation of 4He Tetramer Ground and Excited States Using Realistic 4He–4He Potentials

We calculated binding energies and wave functions of the ⁴He tetramer ground and excited states employing various realistic ⁴He?⁴He potentials which includes the currently most accurate one with the adiabatic, relativistic, QED and residual retardation corrections. We used our Gaussian expansion method (GEM) for ab initio variational calculations of few-body systems. We found that precisely the same shape of the short-range correlation (r _ij < 4Å) in the dimer appear in the ground and excited states of trimer and tetramer. The four kinds of the binding energies of the trimer and tetramer ground and excited states, ${B_3^{(0)}, B_3^{(1)}, B_4^{(0)}}$ and ${B_4^{(1)}}$ , for the different potentials exhibit perfect linear correlations over the range of binding energies relevant for ⁴He atoms; namely, six types of the generalized atomic Tjon lines were observed.     

Development of Charged.Particle Detector and Its Application in Shenzhou-5 Manned Spacecraft

The measuring and monitoring of the radiation environment of earth‘s space have very important significance for developing space science and application techniques. The measurement of space charged particle radiation includes mainly two aspects: (1) measurement of energy spectra and flux of protons and electrons; (2) identification of particle species lighter than Fe and measurement of energy spectra. Charged particle spectroscope consisting of semiconductor detectors was usually used for the measurements mentioned above.     

Study of the 3He(4He,γ)7Be and 3H(4He,γ)7Li Reactions in an Extended Two-Cluster Model

 The ³He(⁴He, γ)⁷Be and ³H(⁴He, γ)⁷Li reactions are studied in an extended two-cluster model which contains α + h/t and ⁶Li + p/n clusterizations. We show that the inclusion of the ⁶Li + p/n channels can significantly change the zero-energy reaction cross sections, S(0), and other properties of the ⁷Be and ⁷Li nuclei, like the quadrupole moments Q. However, the results agree with the known correlation trend between S(0) and Q. Moreover, we demonstrate that the value of the zero-energy derivatives of the astrophysical S-factors are more uncertain than currently believed. Received June 17, 1999; revised February 22, 2000; accepted for publication April 17, 2000     

Production of Λ hypernuclei in π+ A interactions

The production of Λ hyperons in π⁺ A interactions is studied on the basis of the intranuclear-cascade model, and the excitation-energy, momentum, angular-momentum, charge, and mass distributions of the ensemble of product hypernuclei are determined. The decay of excited hypernuclei via particle emission and fission is considered. It is shown that, for the production of heavy Λ hypernuclei, the optimal momentum of the incident π⁺ meson is about 1 GeV/c. The cross section of the channel in which heavy-nucleus decay induced by a π⁺ meson is accompanied by the emission of a K ⁺ meson is estimated, and it is proposed to use the reaction (π⁺, K ⁺ f) in measurements of the fission barrier in hypernuclei and of their level density.     

Energetics of He and H Atoms in W–Ta Alloys: First-Principle Calculations

Properties of various defects of He and H atoms in W-Ta alloys are investigated based on density functional theory. The tetrahedral interstitial site is the most configured site for self-interstitial He and H in W and W-Ta alloys. Only a single He atom favors a substitutional site in the presence of a nearby vacancy. However, in the coexistence of He and H atoms in the presence of the vacancy, the single H atom favors the tetrahedral interstitial site(TIS) closest to the vacancy, and the He atom takes the vacancy center. The addition of Ta can reduce the formation energy of TIS He or H defects. The substituted Ta affects the charge density distribution in the vicinity of the He atom and decreases the valence electron density of the H atoms. A strong hybridization of the H s states and the nearest W d state s exists in W_(53)He_1 H_1 structure. The sequence of the He p projected DOS at the Fermi energy level is in agreement with the order of the formation energy of the He-H pair in the systems.