Spectrally selective optical pumping in Doppler-broadened cesium atoms

The D1 line spectrally selective pumping process in Doppler-broadened cesium is analyzed by solving the optical Bloch equations. The process, described by a three-level model with the Λ scheme, shows that the saturation intensity of broadened atoms is three orders of magnitude larger than that of resting atoms. The |Fg = 3 〉→ |Fe = 4 〉resonance pumping can result in the ground state |Fg = 4 〉, mF = 4 〉sublevel having a maximum population of 0.157 and the population difference would be about 0.01 in two adjacent magnetic sublevels of the hyperfine (HF) state Fg = 4. To enhance the anisotropy in the ground state, we suggest employing dichromatic optical HF pumping by adding a laser to excite D1 line |Fg = 4 〉→ |Fe = 3 〉transition, in which the cesium magnetometer sensitivity increases by half a magnitude and is unaffected by the nonlinear Zeeman effect even in Earth's average magnetic field.     

The Inversionless Amplification in a Tripod System of SrRb Atoms in a Magneto-optical Trap

The probe transmission spectra around the atomic transition 52S1/2,F = 2 → 52P3/2,F = 2 of 87Rb are measured in a magneto-optical trap by adding a coupling field around the atomic transition 52S1/2, F = 2 → 52 P3/2, F1 = 2. The inversionless amplification is observed in the spectrum over the atomic transition 5 2 S1/2, F = 2 → 52pa/2, Fr = 2. The tripod eleetromagnetically induced transparency is proposed to account for the ampli- fication feature, in which population distributions among these related atomic levels play an important role.     

Negative Parity Bands and Signature Splitting Inversion in ^80Rb

High spin states in ^80Rb were studied via the ^65Cu ^19F, ^66Zn ^180 and ^68Zn ^160 reactions. The 75-MeV ^19F,76-MeV ^180 and 80-MeV ^160 beams were provided by the CIAE HI-13 Tandem accelerator and the JAERI Tandem accelerator. The prompt γ-γ coincidence and the directional correlation from oriented nuclei (DCO)were measured by the detector arrays in CIAE and JAERI. Twenty-three new states with 28 new transitionshave been assigned to ^80Rb. The states were observed up to spins of 20^ and 22^- in the α= 0 branch for thepositive and negative parity yrast bands respectively. The negative parity non-yrast bands were significantlyextended up to spins of 22^- and 15^-. The band crossings with frequencies 0.51 MeV and 0.61 MeV in the α= 0cascade were observed for the first time. The signature splitting was observed in both negative parity bands. Thesignature inversions at spins of about 7h and 15h were observed.     

Combined fit to BABAR and Belle Data on e^＋e^- →φπ^＋π^- and φf0（980）

A combined fit is performed to the BABAR and Belle measurements of the e^＋e^- →φπ^＋π^- and φf0（980） cross sections for center-of-mass energy between threshold and 3.0 GeV. The resonance parameters of the φ（1680） and Y（2175） are determined. The mass is （1681-12^＋10） MeV/c^2 and the width is （221-24^＋34） MeV/c^2 for the φ（1680）, and the mass is （2117-49^＋59） MeV/c^2 and the width is （164-80^＋69） MeV/c^2 for the Y（2175）. This information will shed light on the understanding of the nature of the excited φ and Y states observed in e＋e- annihilation.     

Study of new boson W±1 in the Minimal Higgsless Model at the LHC

The Minimal Higgsless Model predicts the existence of new vector gauge boson W1^±, By the process PP →W1^±qq →W^±Z^0qq, Z^0→ 1^＋1^-, W^±→ qq （1=e,μ; q is hadronized to be jets）, we study the sensitivity of searching for this possible vector gauge boson in the level of generator events of signal and backgrounds, then give integrated luminosity required to discover 5σ signal as a function of W1^± mass. The generator for the signal PP → W1^±qq →W^±Z^0qq at tree level is developed with the Minimal Higgsless Model and then interfaced with PYTHIA for the patton showers and hadronization. The backgrounds are produced with MadGraph and PYTHIA.     

Trapping of Neutral^87Rb Atoms on an Atomchip

We report an experiment of trapping of neutral ^87Rb atoms on a self-made atomchip. The H-shaped atomchip is made by magnetron sputtering technology, which is different from the atomchip technology of other teams. We collect 3×10^6 ^87Rb atoms in the mirror magneto-optical trap （MOT） using the external MOT coils, and 1×10^5 ^87 Rb atoms are transferred to U-MOT using U-shaped wire in chip and a pair of bias coils.     

Charmonium results from BES

Using ～ 14 × 10^6 ψ（2S） and ～ 58 × 10^ J/ ψ data collected at BES Ⅱ/BEPC, the branching fraction of ψ（2S）→Ω-Ω^＋ is measured with about 5a statistical significance. The A electric dipole and ∧ decay parameter are studied using the decay J/ψ →∧∧→ ppπ^＋π^-. Using （106±3）× 10^6 ψ（2S） decays collected at BESⅢ/BEPC Ⅱ, we have obtained some interesting physics results. The branching fractions of XcJ→π^0π^0, ηη are measured with precision improved. The mass and width of he（l^1P1） state, together with the branching fractions of Br（ψ（2S） →π^0hc） and Br（hc →γηc） are the first measurements. Surprisingly, the decays of Xc1→φφ, ωω, and ωφ are firstly observed in BESⅢ data.     

Deformed Potential Energy of Super Heavy Element Z = 120 in a Generalized Liquid Drop Model

The macroscopic deformed potential energy for super-heavy elements Z=120 is determined within a generalized liquid drop model (GLDM). The shell correction is calculated with the Strutinsky method and the microscopic single particle energies are derived from the shell model in an axially deformed Woods-Saxon potential with the same quasi-molecular shape. The total potential energy of a nucleus is calculated by the macro-microscopic method as the summation of the liquid-drop energy and the Strutinsky shell correction. The theory is adopted to describe the deformed potential energies in a set of cold reactions. The neck in the quasi-molecular shape is responsible to the deep valley of the fusion barrier due to shell corrections. In the cold fusion path, the double-hump fusion barrier is predicted by the shell correction and complete fusion events may occur. The results show that some of projectile-target combinations in the entrance channel, such as ^50Ca ^252Fm→120 and 58Fe 244 pu→^302 120 , favour the fusion reaction, which can be considered as candidates for the synthesis of super heavy nuclei Z=120 and the former might be the best cold fusion reaction to produce the nucleus ^302 120among them.     

Quantum coherent effects in multi-Zeeman-sublevel atomic systems

This paper reports the experimental results on electromagnetically induced absorption （EIA） spectra observed in the system which does not satisfy completely the conditions given by Lezama et al [1999 Phys. Rev. A 59 4732]. EIA signals on the transitions in the Cs D2 line are able to be observed, where Fg ←→ Fe = Fg-1 as open systems. Theoretical model of Lezama et al is good for the case Fg ←→ Fc = Fg ＋ 1, considering spontaneous transfer of atomic coherences or populations this model is not able to explain our experimental results obtained in the case Fg ←→ Fe = Fg - 1. This paper offers a theoretical model which is able to well explain the case Fg ←→ Fc = Fg - 1. It also uses this theoretical model to explain the split and shift of EIA peaks, which have been obtained in experiments.     

Two-photon spectrum of~(87) Rb using optical frequency comb

The high precision two-photon excitation measurements for 5S1/2(F87g = 2) to 5D5/2(Fe = 4 to 1) ofRb are performed by using an optical frequency comb.The two counter-propagating femtosecond pulses(5S1/2→5P3/2at 780 nm,and 5P3/2→5D5/2at 776 nm) act on87 Rb vapor,and the Doppler broadened background signal is effectively eliminated.The temperature and power dependences of the two-photon spectrum are studied in this paper.     

pp final state interaction in J/ψ →γpp

The phenomenon of the near ppˉ-threshold enhancement observed in the J/ψ→γ pp decay is studied by using the enhancement factor method with a simpler one-pion-exchange potential between p and p. The Jost function caused by the mentioned potential is perturbatively calculated in the zero-th order approximation, and the corresponding enhancement factor is obtained. It is found that such a final state interaction offers an important contribution to the decay width near the ppˉ-threshold, although it is not large enough. To explain the decay data, a phenomenological factor G(p) with the form of 285500/(m 2 π + p 2 ) should be introduced. A further calculation including the p-dependent bare T -matrix, a more realistic N ˉ N potential and the contribution from the higher-order wave functions would provide a better understanding of the decay data and even the existence of the baryonium ppˉ. The near ppˉ-threshold behavior of the decay width in the J/ψ→π 0 pp process is also discussed.     

Broadband Infrared Luminescence of Ni^2＋ in Petalite-Type Transparent Glass Ceramics

Transparent Ni^2＋-doped magnesium aluminosilicate glass ceramics are prepared. The formation of petalite-type crystallites in the glass ceramics is confirmed by x-ray diffraction. Broadband infrared luminescence centred at around 1235nm with full width at half maximum （FWHM） of about 300nm is observed from the Ni^2＋-doped glass ceramics. The observed infrared emission could be attributed to the ^3T2（F） → ^3A2（F） transition of octahedral Ni^2＋ ions in petalite-type crystallites. Theproduct of the fluorescence lifetime and the stimulated emission cross sections is 1.2 ×10-24 cm^2s.     

Luminescent Properties of Eu^3＋—Doped Yttrium Oxide Chloride Embedded in Nanoporous Glass

The photoluminescence of Eu^3 -doped yttrium oxide chloride embedded in nanoporous glass has been observed.In comparison with those in the powder phosphor,the emission lines of Eu^3 ions becom much broader and lueshift was observed in the lines due to ^5D0→^7F2 transitions and the Eu-O charge transfer excitation band.The ratio intensities of the ^5D0→^7F1 transitions to the ^5D0→^7F2 transitions of Eu^3 ion become higher and change at different excitation excitation wavelengths,such as 393nm and 254nm.The two excitation wavelengths belong to the 4f→4f transition of the Eu^3 ion and the Eu-O charge transfer,respectively,This material may be developed into a new luminescent glass.     

The Quantum Coherence Effects in Degenerate Two-level Atomic System

The quantum coherence effects of the transition Fe = 2←→Fg = 3 depending on the polarization of the coupling and probe beam are observed in a Cs vapor cell. The splitting of electromagnetically induced transparency （EIT） window is observed when the degeneracy of two-level system is broken using a magnetic field. It is also shown that the splitted transparency points of two of three windows are shifted with the intensity of magnetic field （ i. e. Zeeman splitting in the upper and lower levels ） increasing. On the contrary, when we fix the intensity of magnetic field, and increase the Rabi frequency of the coupling beam, the splitted transparency peaks become wider. A qualitative agreement between experiment and theory is found.     

Infrared diode laser spectroscopy of O2–N2O van der Waals complex in the v1 symmetric stretch region of N2O

The rovibrational spectrum of O2–N2O van der Waals complex is measured in the ν1 symmetric stretch region of N2 O monomer using a tunable diode laser spectrometer. The complex is generated by a slit-pulsed supersonic expansion with gas mixtures of O2, N2 O, and He. Both a- and b-type transitions are observed. The effective Hamiltonian for an open-shell complex consisting of a diatomic molecule in a ^3Σ electronic state and a closed-shell partner is used to analyze the observed spectrum. Molecular constants in the vibrationally excited state are determined accurately. The band-origin of the spectrum is determined to be 1284.7504（25） cm^-1, red-shifted from that of the N2 O monomer by ～ 0.1529 cm^-1.     

Lifetime Measurement of Cold Atoms in an Integrating Sphere

We present an experimental measurement of the lifetime of the cold ^87 Rb atoms in an integrating sphere. The atoms are cooled by the diffuse light which is generated by the diffuse reflection of laser beams in the integrating sphere. Our result shows that the lifetime is primarily determined by the free fall of the cold ^87Rb atoms, and its half-life can reach 40 ms, which is suitable for many experiments, especially for a cold atom clock.     

Observation of a p mass threshold enhancement in ψ′→π+π-J/ψ(J/ψ→γp) decay

The decay channel ψ→π+π-J/ψ(J/ψ→γp) is studied using a sample of 1.06×108 ψ events collected by the BESIII experiment at BEPCII. A strong enhancement at threshold is observed in the p invariant mass spectrum. The enhancement can be fitted with an S-wave Breit-Wigner resonance function with a resulting peak mass of M =1861+6-13 (stat)+7-26 (syst) MeV/c2 and a narrow width that is Γ <38 MeV/c2 at the 90% confidence level. These results are consistent with published BESII results. These mass and width values...     

Masses and Widths of Light Scalar Mesons in Chiral Perturbation Theory

Based on the diquark model, we assume that the light scalar mesons are q^2q^-2 states rather than qq^-. The chiral effective Lagrangian for the light scalar meson is constructed, and the mass relations are obtained： the isotriplet （a0） and the isosinglet （f0） are the heaviest and are degenerate, the isodoublets （κ） are heavier and the other isosinglet （σ） is the lightest; and 2Mκ^2 = Mα0^2＋ Mσ^2. Using experimental value for a0 and σ mass, we obtain Mκ=794 MeV, which is consistent with the experimental value. Then taking Г（a0^0 →ηπ^0） = 90 MeV and Г（f0→π^0π^0） = 20 MeV, we get the width of σ is： Г（σ0→π^＋π^-）= 150 MeV.     

Search for the chiral Band in the N=71 Odd—odd Nucleus ^126Cs

High-spin states in ^126Cs are studied via the ^116Cd(^14N,4n) reaction at a beam energy of 65MeV.The sideband of the πvh11/2 yrast band,a ΔI=2 band known from previous study,is developed into a ΔI=1 coupled structure at low spins.This sideband is assigned to be built on the same configuration as the yrast band according to the measured ratios of directional correlation of orientation and observed alignment properties.On the basis of comparisons with the previously proposed chiral doublet bands for ^128,130Cs,the observed two πh11/2 vh11/2 bands are proposed to be candidates for chiral doublet bands in ^126Cs.     

Broadband Near-Infrared Emission from Transparent Ni^2＋ -Doped Sodium Aluminosilicate Glass Ceramics

Broadband near-infrared emission from transparent Ni^2＋-doped sodium aluminosilicate glass-ceramics is observed. The broad emission is centred at 1290nm and covers the whole telecommunication wavelength region （1100- 1700hm） with full width at half maximum of about 340hm. The observed infrared emission could be attributed to the 3T2（F） → 3A2（F） transition of octahedral Ni^2＋ ions that occupy high-field sites in nanocrystals. The product of the lifetime and the stimulated emission cross section is 2.15 × 10^-24 cm^2s. It is suggested that Ni^2＋- doped sodium aluminosilicate glass ceramics have potential applications in tunable broadband light sources and broadband amplifiers.