The Strong Three-body Weak Interaction Contribution in the Nonmesonic Weak Decay of p-shell Λ Hypernuclei

The fundamental motivation to study the non-mesonic weak decay (NMWD) of hypernuclei is that it provides the unique means for study of baryon–baryon weak interaction in SU3 _f symmetry group. The new channel of NMWD, namely the recently confirmed three-body channel, seems to have a surprisingly big branching ratio so that it makes its accurate measurement prerequisite of the baryon–baryon weak interaction study. We report a new result of ${\Gamma_{2N}(^{11}_{\Lambda} {\rm B})}$ from E508 experiment of KEK-PS, though preliminary yet, which agrees with the previous result of ${^{12}_{\Lambda}}$ C from the same experiment, those from FINUDA experiment and those of the recent theoretical predictions.     

Rotation—Vibration Coupling in the Geometric Representation of the Interacting Boson Model

We discuss rotation-vibration coupling in the geometric representation of the interacting boson model (IBM).The Hamiltonian,the relations between the IBM parameters and geometric parameters,and the method of calculation are given so that practical applications of geometric representation may become possible.     

Description of Superdeformed Bands of the Nuclei in A—80 Mass Region

Within the supersymmetry scheme inchuding many-body interactions and a perturbation possessing the SO(5) (or SU(5)) symmetry on the rotational symmetry,the superdeformed (SD) bands of the nuclei in the A-80 mass region are investigated systematically.Quantitatively good results of the γ-ray energy spectra and the dynamical monents of inertia are obtained.It is shown that the supersymmetry approach is powerful to describe not only the generic rotational property,but also the characteristic of the triaxial SD band simultaneously.     

Impurity effects of the Λ hyperon in the hypernuclear systems Λ25Mg and Λ29Si

Based on the beyond-mean-field Skyrme-Hartree-Fock model,impurity effects of the Λ hyperon in the hypernuclear systems Λ25Mg and Λ29Si are investigated,respecti...     

Excitation and structure of hypernuclear resonances in (K −,π ¯0)-reactions on 1p-shell nuclei

The available experimental data on the excitation functions (EF) of the 1p-shellΛ-hy-pernuclei in (K ^?, π^?) reactions atθ _π = 0^° has been analysed in terms of shell model and weak coupling scheme. It is substantiated by the experimental data on the neutron spectroscopic factors and on the fragmentation of nuclear hole excitations. The pronounced nuclear spectroscopic characteristics in the hypernuclear spectra are indicative of a weak coupling ofΛ-hyperon with nuclear subsystem. The analysis has made it possible to determine the difference is single-particle energies ofΛ-hyperon in the 1p- and 1s-states and to obtain additional evidence for the smallness of theΛ-nucleus spin-orbit interaction. The resonance structure of EF of hypernuclei, which were not studied in (K ^?,π ₀ ^? ) reactions, is predicted. The interrelated aspects of the studies of the (K ^?,π ₀ ^? ), (K ^?,π ₀ ^? β^′), and (K ^?, π⁺) reactions which are of interest to spectroscopy ofΛ-andΣ-hypernuclei are discussed.     

Laser spectroscopy of jet－cooled CuF in visible region

The laser-induced fluorescence excitation spectra of jet-cooled CuF have been recorded in the range of 19000－21470cm^{-1}, in which the CuF radicals were produced by the reaction of SF_6 with copper atoms from a dc discharge-sputtering source under supersonic jet conditions. Eight observed vibronic transition bands have been assigned as the transition from the ground state X(^1Σ^+) to B(^1Σ^+), C(^1Π) and an unreported upper state. The rotational structure of all observed bands has been analysed at the estimated rotational temperature 80K. We determined the newly observed band to be the (^1Π, v=1)－X(^1Σ^+v=0) transition according to the character of the rotational structure and the isotopic shift analysis. In addition, the lifetimes of the states involved in these bands were measured.     

Isospin Effect of Coulomb Interaction on Momentum Dissipation in Intermediate Energy Heavy Ion Collisions

We investigate the isospin effect of Coulomb interaction on the momentum dissipation or nuclear stopping in the intermediate energy heavy ion collisions by using the isospin-dependent quantum molecular dynamics model. The calculated results show that the Coulomb interaction induces obviously the reductions of the momentum dissipation. We also find that the variation amplitude of momentum dissipation induced by the Coulomb interaction depends sensitively on the form and strength of symmetry potential. However, the isospin effect of Coulomb interaction on the momentum dissipation is less than that induced by the in-medium nucleon-nucleon cross section.In this case, Coulomb interaction does not change obviously the isospin effect of momentum dissipation induced by the in-medium two-body collision. In particular, the Coulomb interaction is preferable for standing up the isospin effect of in-medium nucleon-nucleon cross section on the momentum dissipation and reducing the isospin effect of symmetry potential on it, which is important for obtaining the feature about the sensitive dependence of momentum dissipation on the in-medium nucleon-nucleon cross section and weakly on the symmetry potential.     

奇异性核物理前沿问题

简要评述奇异性核物理的几个前沿问题,包括Λ超核能谱精细结构与ΛN相互作用提取问题,自由YN势的改进问题、K核问题、Σ超子-核势问题、Λ超子-Λ超子相互作用强度问题、中子星内部奇异粒子成分问题等。     

Progress in p-shell A hypernuclear spectroscopy

The strangeness nuclear physics is an important branch of nuclear physics. The spectroscopic study of A hypernuclei has been used as a tool for investigating the A-N interaction as well as probing the nuclear interior structure. In this paper some high-lights and open questions in the spectroscopic study of p-shell A hypernuclei are presented.     

Baryonic decay and 1p-shell hypernuclear spectroscopy

The detailed discussion of baryonic decay channels is presented. Levels built on sp^–1, PP^–1 and ss^–1 configurations are considered. The results presented are obtained in the calculations based on the Translationally Invariant Shell Model which automatically includes some intruder states through the kinematic correlations. The role of the intruder states in the proton decay is discussed. The evolution of the baryonic decay width with increasing nucleon number A in the 1p-shell hypernuclei is traced. Hypernuclear decays into the bound excited states either of secondary hypernuclei or nuclei are revealed. Information which could be extracted from the de-excitation of the baryonic decay products whenever they were measured is discussed. From the suggested new set of theN interaction parameters for the sp^–1 configuration some new information on the proton decay of the ¹² C hypernucleus pp^–1 low-lying levels is given.We would like to express our sincere thanks to R. Chrien, D. Davis, H. Ejiri, K. Itonaga, J. Milener, T. Motoba, O. Richter, M. Sotona and Yu. Smirnov for many illuminating discussions. One author (L.M.) is indebted to Prof. T. Motoba for warm hospitality in Kyoto and Osaka, where a part of this report was prepared.     

Progress in hypernuclear physics

The recent progress in hypernuclear physics is discussed in this paper. The topics include recent results on hypernuclear gamma-ray spectroscopy, non-mesonic weak decay, and double- hypernuclei. Future prospects at the 50 GeV PS are also discussed.Received: 30 September 2002, Published online: 22 October 2003PACS: 21.80. + a Hypernuclei - 25.80.-e Meson- and hyperon-induced reactions     

双光梳光谱学研究进展

双光梳光谱仪具有超高光谱分辨率、超快采样时间的特性,是研究分子吸收光谱的有力工具。文章介绍了双光梳光谱仪的基本原理以及它与传统傅里叶光谱仪的区别,叙述了几种典型的双光梳光谱仪构成及其用于测量分子吸收光谱的实验结果,并对双光梳光谱学做了详细说明。随着中红外光梳和中红外探测器技术的进一步发展,双光梳光谱学将会在大气污染监测、呼吸气体检测等重要的国计民生领域得到越来越广泛的应用。     

A theoretical overview of hypernuclear weak decay

The physics of the weak decay of hypernuclei is briefly reviewed from a theoretical point of view. Special regard is devoted to the recent progress concerning the determination of the non-mesonic decay widths and the asymmetry parameters. Convincing evidence has been achieved for a solution of the long-standing puzzle on the ratio Γ_n/Γ_p. Very recently, it has been shown that the exchange of a ππ pair in the weak mechanism plays a crucial role in explaining the discrepancies between theory and experiment on the decay asymmetries.     

Cluster model of s- and p-shell ΛΛ hypernuclei

The ΛΛ binding energy (B _ΛΛ) of the s- and p-shell hypernuclei are calculated variationally in the cluster model and multidimensional integrations are performed using Monte Carlo. A variety of phenomenological Λ-core potentials consistent with the Λ-core energies and a wide range of simulated s-state ΛΛ potentials are taken as input. The B _ΛΛ of _ΛΛ⁶He is explained and _ΛΛ⁵He and _ΛΛ⁵H are predicted to be particle stable in the ΛΛ-core model. The results for s-shell hypernuclei are in excellent agreement with those of non-VMC calculations. The _ΛΛ¹⁰Be in ΛΛαα model is overbound for combinations of ΛΛ and Λα potentials. A phenomenological dispersive three-body force, V _Λαα, consistent with the B _Λ of _Λ⁹Be in the Λαα model underbinds _ΛΛ¹⁰Be. The incremental ΔB _ΛΛ values for the s- and p-shell cannot be reconciled, consistent with the finding of earlier analyses.      

激光诱导击穿光谱技术及应用研究进展

激光诱导击穿光谱（LIBS）技术是一种基于原子发射光谱学的元素定性、定量检测手段。本文介绍了LIBS技术的原理、应用方式、检测元素种类及检测极限;综述了该项技术在固体、液体、气体组分检测方面的技术发展,以及在环境检测、食品安全、生物医药、材料、军事、太空领域的应用进展。最后,提出了高功率、高稳定的激光光源和准确的定量分析方法是LIBS技术目前所面临的问题和挑战。     

红外光谱法检测生物大分子损伤的研究进展

红外光谱技术由于其灵敏度高和对样品的非破坏性等优点已成为研究生物大分子损伤的重要工具。蛋白质、脂质和核酸等受到损伤时,其红外光谱特征吸收峰的峰位、峰型和峰强会发生变化,这为检测生物大分子损伤并进一步揭示相关疾病的发生、发展及早期预防提供了依据。还综述了近年来使用红外光谱法检测生物大分子损伤的研究进展,介绍了利用傅里叶变换红外光谱、衰减全反射傅里叶变换红外光谱和傅里叶红外显微等技术在蛋白质二级结构、膜脂流动性和离子通透性以及药物对DNA的作用机制等领域的应用,以及相关的定性和定量分析方法进行了评述,提出了目前红外光谱分析技术中存在的问题,并对今后红外光谱在生物医学领域中的应用前景作了展望,指出疾病早期诊断、红外光谱联用以及定量分析技术等将成为红外光谱领域未来的研究热点。     

Correlations in hypernuclear matter

We investigate short-range correlations in nuclear and hypernuclear matter. Self-energies due to short-range correlations and their influence on the nucleon and Λ -hyperon spectral functions are described in an approach accounting for a realistic treatment of mean-field dynamics and a self-consistently derived quasi-particle interaction. Landau-Migdal theory is used to derived the short-range interaction from a phenomenological Skyrme energy density functional, subtracting the long-range pionic contributions to the nucleonic spectral functions. We discuss our results for different hyperon-baryon ratios to show the influence of strangeness on the correlations in hypernuclear matter.     

A phenomenological woods-saxon potential for p-shell nuclei

The parameters of a Woods-Saxon potential well have been determined for ten p-shell nuclei by fitting the electron scattering form factors and single-particle binding energies. The resulting radius shows, for all but very light nuclei, a regular $\text{A}\text{1}\text{3}$ dependence while the depth smoothly decreases with the increasing proton energy. The observed energy dependence may be ascribed to the non-locality of the HF potential. An energy-independent non-local potential, compatible with elastic electron and proton scattering, is proposed in the energy range ?50 to +50 MeV.