高自旋同质异能态束流的产生和应用

论述了高自旋同质异能态束流的物理意义.以RINKEN的HSIB为例,简略地叙述了高自旋同质异能态束流的产生、分离、传输及纯化的方法,并对高自旋同质异能态束流诱发核反应中放出的γ射线探测技术进行了论述. The physical motivations with high spin isomer beams were introduced. Taking HSIB of RIKEN as an example, the methods to produce, separate, transport and purify high spin isomer beams were described briefly, and the detection of γ rays emitted from the reactions induced by the high spin isomer beams was presented. Finally, the progress to develope the high spin isomers in the N =83 isotones as second beams was stressed.     

Partner of η2（1645） in the 11D2 Meson Nonet

In the qq quark model, the states π2（1670） and η2（1645） are assigned as the I1D2 meson nonet. The partner of state η2（1645） needs further confirmation in the experiments. We employ the meson-meson mixing and the Regge trajectory methods to calculate the mass of the partner of state η2 （1645） to be 1879.8 MeV and 1863 ± 24 MeV respectively. We also calculate the strong decay width in the 3po decay model. These predictions can be compared with experiments in the future.     

Intra-acceptor hole relaxation in Be δ-doped GaAs/AlAs multiple quantum wells

This paper studies the dynamics of intra-acceptor hole relaxation in Be δ -doped GaAs/AlAs multiple quantum wells (MQW) with doping at the centre by time-resolved pump-probe spectroscopy using a picosecond free electron laser for infrared experiments. Low temperature far-infrared absorption measurements clearly show three principal absorption lines due to transitions of the Be acceptor from the ground state to the first three odd-parity excited states respectively. The pump-probe experiments are performed at different temperatures and different pump pulse wavelengths. The hole relaxation time from 2p excited state to 1s ground state in MQW is found to be much shorter than that in bulk GaAs, and shown to be independent of temperature but strongly dependent on wavelength. The zone-folded acoustic phonon emission and slower decay of the wavefunctions of impurity states are suggested to account for the reduction of the 2p excited state lifetime in MQW. The wavelength dependence of the 2p lifetime is attributed to the diffusion of the Be atom δ -layer in quantum wells.     

176，178Os新低位激发态的识别

利用在束实验产生具有β^＋/EC衰变性质核素^176，178Ir，分析了在柬实验条件下获得的γ—γ符合数据，识别出了^176Os的4条新能级和13条新γ跃迁、^178Os的5条新能级和14条新γ跃迁。籍助氨喷嘴快速带传输系统，进一步对^176Ir的β’/EC衰变进行了测量，在确认在束测量新γ射线的同时建议了^176Ir的一个低自旋同核异能态。通过两准粒子耦舍的半经验计算，建议了^176，178Ir基态及同核异能态的组态。The γ rays following the β^＋/EC decay of ^176. 178Ir nuclei have been investigated using in-beam γ- ray experiment. A total of 4 new levels, 13 new γ transitions of ^176Os and 5 new levels, 14 new γ transitions of ^178Os were identified. In addition, with the aid of a helium-jet recoil fast tape transport system, the β^＋/EC decay of ^176Ir was further studied, the above new γ rays were proved and an isomer was proposed in ^176Ir. By the semiempirical calculations of two-quasiparticle intrinsic states of odd-odd nuclei, the configurations of ground states and isomeric states were also proposed for ^176, 178Ir     

Measuring DO-D-O mixing in D→Fo(980)K* and more

We investigate the DO-D-O mixing through the doubly Cabibbo suppressed (DCS) channel DO→fO(980)K*O and its charge conjugate channel,in which the K*O meson is reconstructed in both K+π- and KsπO final state.Although the decay DO→ fo(980)K* has a small branching ratio,the final state mesons are relatively easy to identify.The fo(980) meson can be replaced by the S-wave π+π- state,or a longitudinally polarized vector meson pO.All mixing parameters,including the mass difference and decay width difference,can be extracted by studying the time-dependent decay width of these channels.We show that the method is valid in all regions for mixing parameters and it does not depend on the strong phase difference.     

Monitoring the reaction between AICl3 and o-xylene by using terahertz spectroscopy

Terahertz time-domain spectroscopy （THz-TDS） is used to study the interaction between AlCl3 and o-xylene in a temperature range from 300 K to 368 K. For comparison, the three isomers of o-, m-, and p-xylene are measured by using THz-TDS. The o-xylene carries out isomerization reaction in the presence of catalyst AlCl3. The absorption coefficient of the mixed reaction solution is extracted and analyzed in the frequency range from 0.2 THz to 1.4 THz. The temperature dependence of the absorption coefficient, which is influenced by both the dissolution of AlCl3 and the production of the two other isomer resultants, is obtained, and it can indicate the process of the isomerization reaction. The results suggest that THz spectroscopy can be used to monitor the isomerization reaction and other reactions in chemical synthesis, petrochemical and biomedical fields.     

The mass of the isodoublet of the 2^1S0 meson nonet revisited

In the qq quark model, the states π（1300）, η（1295） and η（1475） are assigned as the 2^1S0 meson nonet. The mass of the isodoublet remains interesting and needs further confirmation in experiments. This paper employs the phenomenological trajectory on the （N, M^2）-plot and meson meson mixing methods to calculate the mass of this state, the calculated results are 1341 MeV and 1311.58 ± 59 MeV respectively. These predictions can be compared with experiments in the future.[第一段]     

Multiqubit Nonlocal Operation and Physical Implementation

We propose a scheme of preparing four-atom cluster states in thermal cavity. Four two-level atoms, three thermal cavities and classical field are used in the scheme. Compared with previous schemes, the scheme can be generalized to n-atom cluster states and the successful probability can be 100%, which the system of the photon can never reach. In addition, the system is insensitive to cavity decay and the thermal field. Using the four-atom cluster state, we also propose a simpler scheme for remote controlled not gate （CNOT）, in which we detect the separate states instead of the joint-Bell states measurement.     

Measuring D~0-~0mixing in D→f_0(980)K~* and more

We investigate the D0-0 mixing through the doubly Cabibbo suppressed (DCS) channel D0 →f0(980)K0 and its charge conjugate channel, in which the K0 meson is reconstructed in both K π- and KSπ0 final state. Although the decay D0 →f0(980)K* has a small branching ratio, the final state mesons are relatively easy to identify. The f0(980) meson can be replaced by the S-wave π π- state, or a longitudinally polarized vector meson ρ0. All mixing parameters, including the mass difference and decay width difference,can be extracted by studying the time-dependent decay width of these channels. We show that the method is valid in all regions for mixing parameters and it does not depend on the strong phase difference.     

Excitation and decay dynamics of 1s2s inner-shell double-vacancy states of neon atoms

The photo-excitation and Auger decay processes of inner-shell double vacancy states 1s2s2p^6（1,3^S）3s3p of neutral neon atoms have been studied theoretically. Multi-configuration Dirac-Fock （MCDF） calculations have been carried out, with electron correlation effects taken into consideration. The relaxation of core and excited orbitals and configuration interaction are found to be crucial to creating the double vacancy states by single photo-absorption. The predominant decay paths for the double vacancy states turn out to be of the LLM Auger decay to 1s 2s^22p^53s（3p）, KLL Auger decay to 1s^22s2p^43s3p, and KLM Auger decay to 1s^22p^63s（3p）. They lead to further Auger decay, creating the neon ions of multiple charge states. For both double and single vacancy states the spectator type of Auger process is dominated in all the Auger decay processes. Theoretical Anger electron spectra are presented for further investigations, experimental and theoretical.     

Size-dependent optical properties and carriers dynamics in CdSe/ZnS quantum dots

Size-dependence of optical properties and energy relaxation in CdSe/ZnS quantum dots （QDs） were investigated by two-colour femtosecond （fs） pump-probe （400/800 nm） and picosecond time-resolved photoluminescence （ps TRPL） experiments. Pump-probe measurement results show that there are two components for the excited carriers relaxation, the fast one with a time constant of several ps arises from the Auger-type recombination, which shows almost particle sizeindependence. The slow relaxation component with a time constant of several decades of ns can be clearly determined with ps TRPL spectroscopy in which the slow relaxation process shows strong particle size-dependence. The decay time constants increase from 21 to 34 ns with the decrease of particle size from 3.2 to 2.1 nm. The room-temperature decay lifetime is due to the thermal mixing of bright and dark excitons, and the size-dependence of slow relaxation process can be explained very well in terms of simple three-level model.     

Mechanical effects of light on the Ξ-type three-level atom in a high-finesse optical cavity

A theoretical study is carried out for the modification and implication of the effect on the Ξ-type three level atom in a high-finesse optical cavity driven by light field including spontaneous emission and the cavity decay. Analytic expressions for the dipole force, the friction force, the optical potentials and the friction coefficient are obtained. Then the numerical and graphical methods are used to investigate the friction coefficient with the controlling parameters. It is shown that the friction coefficient is strongly dependent on the controlling parameters. The cooling rate can increase by one order of magnitude more than that of a two-level atomic system. The reason can be given using the dressed states and the Sisyphus cooling mechanism, which would stimulate further experimental investigations.     

Controlling chaos based on an adaptive nonlinear compensator mechanism

The control problems of chaotic systems are investigated in the presence of parametric uncertainty and persistent external disturbances based on nonlinear control theory. By using a designed nonlinear compensator mechanism, the system deterministic nonlinearity, parametric uncertainty and disturbance effect can be compensated effectively. The renowned chaotic Lorenz system subjected to parametric variations and external disturbances is studied as an illustrative example. From the Lyapunov stability theory, sufficient conditions for choosing control parameters to guarantee chaos control are derived. Several experiments are carried out, including parameter change experiments, set-point change experiments and disturbance experiments. Simulation results indicate that the chaotic motion can be regulated not only to steady states but also to any desired periodic orbits with great immunity to parametric variations and external disturbances.     

量子无规运动与核耗散

从动力学对称性观点出发考察了量子规则运动与无规运动 .用能级动力学研究了从量子规则运动向量子无规运动的过渡 ,给出了导致能级混沌的条件 ,揭示了造成能级混沌的机制 .用混沌态矢的特征解释了原子核的各态历经集体态的衰变特性 .研究了重离子碰撞中核耗散与动力学对称性破坏之间的关系. Quantum regular and irregular motions are investigated from the viewpoint of dynamical symmetry. The transition from quantum regular motion to chaotic motion is studied by level dynamics and computer experiments. The conditions for onset of quantum chaos are presented.The mechanism for causing chaotic level spectrum is unveiled. The decay behavior of the nuclear ergodic collective states is explained in terms of the peculiar property of chaotic states. The connection between nuclear...     

126Ce的EC/β+衰变

利用187 MeV的40Ca离子轰击同位素靶92Mo, 由熔合蒸发反应生成目标核126Ce。 藉助氦喷嘴快速带传输系统和X-X-t与X-γ-t符合测量, 首次建立了126Ce的EC/β+衰变纲图。 建议了可能属于126Ce一个高自旋同核异能态的衰变, 其β衰变后布居在与126La的高自旋同核异能态相关的低位能级区, 测定的半衰期是57(9) s。 也建议了可能属于126Ce基态的衰变, 其β衰变后布居在与126La的低自旋同核异能态相关的低位能级区,它的半衰期被测定为12(4) s。 但偶偶核126Ce存在高自旋同核异能态的物理原因还有待进一步探究。 Ce was produced by bombarding an enriched target of 92Mo with 187 MeV 40Ca beam and studiedby using a helium jet fast tape transport system in combination with X-γ and γ-γ coincidencemeasurements. An EC/β+ decay scheme of 126Ce was proposed for the first time. A group of low lying states associated with the low spin isomer in 126La feeding by β decay was possibly from the ground state EC/β+ decay of 126Ce with the measured half-life 12(4) s. Another group of low lying states associated with the high spin isomer in 126La feeding by β decay was possibly from a high spin isomer EC/β+ decay of 126Ce with the measured half-life 57(9) s. However, the physical reason for the existence of a high spin isomer in even-even nucleus 126Ce is still an open problem.     

Dense Coding with Multi-Atom Entanglement Channel in Cavity QED

Dense coding of multi-atom entangled states in cavity QED is studied. If the quantum channel is generalized GHZ states, dense coding can be directly realized in a simply way. As for the partially entangled pure states, we propose a feasible protocol for entanglement concentration, and the emciency of information transmitted is calculated. The schemes are insensitive to the cavity decay and the field state, due to the fact that the interaction here is a large-detuned one between atoms and the cavity.     

Carrier Dynamics Determined by Carrier-Phonon Coupling in InGaN/GaN Multiple Quantum Well Blue Light Emitting Diodes

Phonon sidebands in the electrolumiescence(EL) spectra of InGaN/GaN multiple quantum well blue light emitting diodes are investigated. S-shaped injection current dependence of the energy spacing(ES) between the zero-phonon and first-order phonon-assisted luminescence lines is observed in a temperature range of 100–150 K.The S-shape is suppressed with increasing temperature from 100 to 150 K, and vanishes at temperature above200 K. The S-shaped injection dependence of ES at low temperatures could be explained by the three stages of carrier dynamics related to localization states:(i) carrier relaxation from shallow into deep localization states,(ii) band filling of shallow and deep localization states, and(iii) carrier overflow from deep to shallow localization states and to higher energy states. The three stages show strong temperature dependence. It is proposed that the fast change of the carrier lifetime with temperature is responsible for the suppression of S-shaped feature.The proposed mechanisms reveal carrier recombination dynamics in the EL of InGaN/GaN MQWs at various injection current densities and temperatures.     

Strong decays of P-wave mixing heavy-light 1~+ states

Many P-wave mixing heavy-light 1~+ states have not yet been discovered by experiment, while others have been discovered but without width information, or with large uncertainties on the widths. In this paper, the strong decays of the P-wave mixing heavy-light 1~+ states D0, D~±, D~±s, B0, B~±and Bs are studied by the improved BetheSalpeter(B-S) method with two conditions of mixing angle θ: one is θ = 35.3?; the other is considering a correction to the mixing angle θ =35.3?~+θ_1. Valuable predictions for the strong decay widths are obtained: Γ(D′01)=232 MeV,Γ(D01)=21.5 MeV, Γ(D′_1~±.)=232 MeV, Γ(D_1~±)=215 MeV, Γ(D′_(s1)~±)=0.0101 MeV, Γ(D~±s1)=0.950 MeV, Γ(B′_1~±)=263 MeV, Γ(B~±1) = 16.8 MeV, Γ(B′s1) = 0.01987 MeV and Γ(B_(s1)) = 0.412 MeV. It is found that the decay widths of D~±s1 and Bs1 are very sensitive to the mixing angle. The results will provide theoretical assistance to future experiments.     

Transient responses of transparency in a far-off resonant atomic system

Transient coherent oscillations in a closed Λ system under far-off resonant Raman fields were investigated theoretically. It has been found that the coherent superposition of the ground states can be formed due to the absorption even for initial maximal mixed ground states. The absorption oscillates with a period depending on the two-photon detuning when the system is initially in a transparent state and the two-photon Raman detuning is suddenly changed. The amplitude of the absorption decays with the decay rate of the ground states, which is different from the case when the lasers are applied resonantly. These transient coherent oscillations can be used to measure the relaxation rate of the ground states.     

Radiative leptonic decay B_c~-→τ~-_τγ in the standard model and the two-Higgs-doublet model

We analyze the radiative leptonic Bc decay Bc-→τ-νˉτγ in the Standard Model and the twoHiggs-doublet model using the non-relativistic constituent quark model.The results confirm that this channel is experimentally promising in view of the large number of Bc mesons which are expected to be produced at future hadron facilities.We also find that this decay is sensitive to the parameters of the two-Higgs-doublet model,and it can be tested in future experiments.