2002 Vol. 26, No. 6
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The experimental phenomenon-the helicity inversion of laser (photons) during reflection has been explained based on the quantum theory of the laser (photons) propagation through an optical helix. It is found that the instant process of the laser(photons) reflection on a mirror will produce an extremely high rotation frequency of the wave vector. The coriolis coupling between the spin of the photon and the rotation of the wave vector is the dynamical factor which dominates the process and causes helicity inversion. The implication of the helicity inversion in information theory is also discussed.
We report a measurement of the absolutely inclusive semileptonic branching fractions of D－ and D0 mesons, using a data sample of 22.3pb－1 collected with BES detector at BEPC e+e－ Collider at s=4.03GeV and based on the method of "combinative D+ and D0 single and double tags". The measured values of the branching fractions for D－→e－X and D0→e－X are (21.8±8.5±4.2)% and (8.9±3.0±1,6)%, respectively. The measured ratio of the branching fractions is BF(D－→e－X)/BF(D0→e－X)=2.4±1.7±0.8.
In this paper an important character was found that the final hadron multiplicities of direct J/ψ decays satisfy the same universal mass dependence as that in e+e－→q0q0 continuum events. This indicates that the fragmentation of quark and gluon to hadron follows the same mechanism. We give a reasonable interpretation to final baryon multiplicity that is enhanced by 2.5 times in direct Y decays compared to the continuum through our calculating results. But we cannot find this similar phenomenon in direct J/ψ decays.
In previous calculations of the strong decay of a charmonium,the first-order momentum dependence of the quark propagator is kept. It was found that the finite-size vertex correction to the Γ(J/ψ→3g) process is large. In this paper we calculate the two-gluon decay widths of ηc,χc0 and χc2 by including the full momentum dependence of the quark propagator. Comparing to the zero-order calculation we find that the finite-size vertex correction factor to the two-gluon decay widths of ηc is 1.32,and for the two gluon decays of χc0 and χc2,the vertex correction factors are 1.45 and 1.26, respectively. With the corrected decay widths Γ(ηc→2g) we extract the value as αs(mc)=0.28±0.05 which agrees with that calculated from the Γ(J/ψ→3g) process with the same correction. The finite-size vertex correction to the process Γ(ηc→3g) is not as large as that to the process Γ(J/ψ→3g).
We introduce a quantum antibunching effect. The quantum antibunching effect of the K eigenstates of the K th powere (K≥3) of the annihilation operator in the Q-deformed non-harmonic oscillator is investigated. The physical meaning of the K states are explored. The results show that there is the quantum antibunching effect in all of those states. All of them can be generated by a linear superposition of generalized coherent states produced by the time-dependent Q-deformation non-harmonic oscillator at different instants.
The antibunching effect for the eigenstates of the q-deformed annihilation operator aqk(k≥3) is investigated. Using the numerical method, we have studied the influences of the q-parameter deformation on the effect in the case of k=3. The results show that the eigenstates of aqk exhibit antibunching effect when x=|z|2, i.e. the intensity of the oscillator in q-deformed coherent state, is in values of certain intervals, and the effect is evidently influenced by the values of parameter q. When the intensity of the q-deformed light field is changed stronger gradually, the fluctuation of the photon number in the light field is changed between the classical (or quantum) and the quantum (or classical) properties alternatively.
High spin states in deformed odd-odd 180Ir have been investigated using the 154Sm (31P, 5nγ)180Ir reaction through the measurements of excitation functions at 150, 155, 160, 165 and 170 MeV beam energies, K X-γ and γ-γ coincidences at 160 MeV. A new level scheme composed of 5 rotational bands has been established. According to the band structure characteristics and the deduced in band B(M1)/B(E2) ratios, the quasiparticle configurations and spin and parity have been proposed to the observed bands. The neutron AB crossing is observed at hωc≈0.26 MeV for the π1/2－⊙ν1/2－ and π1/2－⊙ν5/2－ bands. This AB crossing frequency is close to that in the ν5/2－ band of 179Os indicating the loss of intruder nature of the π1/2 - orbit. Gradual alignment gain in both the π9/2－⊙ν7/2+ and π9/2－ν5/2－ bands is observed which is similar to the low spin anomaly in alignment in the πh11/2,πd5/2 and πi13/2 bands of neighboring Ir and Re isotopes. Different alignment properties have been discussed in the framework of cranked shell model, and a larger quadrupole deformation is suggested for the bands with π9/2－ orbit involved.
Present experiment was performed in order to get more information about intermediate energy heavy ion collisions for the further understanding of that how nuclear reaction mechanisms change between the two extreme types of nuclear behaviors, the nuclear collisions at low and high energy. Ba isotopes were produced by 60 MeV/u 18O bombardment of nature uranium via 238U(18O,X) reaction, and then separated from the irradiated U targets by using radiochemical procedure. The accumulative sections of Ba isotopes are obtained through the processing and analyzing of time sequence γ ray spectra. As a result, the two peak phenomenon in the distribution of the Ba isotopes is observed. It can be presumed that the occurrence of the double Gaussian distribution is weakly related to the projectile energy, but closely related to the projectile target combination. Present experiment also implied however, that fragmentation reaction induced by intermediate energy heavy ions followed by radiochemical separation is an efficacious method to produce nuclei far from stability, thereby to study their decay properties.
Under reverse kinematics, elastic scattering of 17F and 18Ne on proton is studied. The experimental differential cross sections were measured. A kind of global optical potential with the CH89 parameters is used to describe the radioactive nucleus as an initial optical potential parameters. The experimental differential cross section data are analyzed by using the theoretical calculation code DWUCK4 with the distorted wave Born approximation and parameter search subroutine ABOD which automatically searches the suitable parameters. Then the optical potential parameters of scattering 17F and 18Ne on proton are obtained. From the analyses of the optimized parameters, the real central potential mean square radii of 17F and 18Ne, 3.239fm and 3.317fm are deduced, respectively.
Based on nuclear reaction models, i.e., the optical model, evaporation model, exciton model and the direct reaction theory, cross sections of (p,xn) reactions and residual nuclei productions for p+209Bi reaction were calculated in energy region from threshold up to 300MeV and a set of proton optical potential parameters for 209Bi up to 500MeV were obtained. The direct inelastic cross sections were calculated with the distorted wave Born approximation theory. Theoretical results show that the direct inelastic cross sections of about 550mb are reasonable.
In the two cases that the deformed nuclear system is regular and chaotic, the spatial temporal evolution of the coherent states of a two dimensional harmonic oscillator system as an initial state was analyzed with the Fourier transformation, especially by comparing the Fourier transformation of the width of the wave packet in the whole time stage with that the wave packet approaching to the saturation in the chaotic system. It was found that since a large number of avoided level crossings destroy the regular structure of the state space of the system, the components in the wave packet are no longer coherent and the motion of the wave packet becomes chaotic. Afterwards, the contribution coming from the different components tends to uniform, the influence of the avoided level crossings on the motion of the wave packet is not obvious also.
Using modified surface delta interaction and enlarging the fp configuration space to include the 1g9/2 states with the positive parity, the deformed Hartree Fock calculations for the six nuclei: 64Ge,66Ge,68Ge,70Se,72Se and 74Se are performed. The ground state and some particle-hole excited configurations are obtained. The approximate angular momentum projected Hartree Fock (PDHF) method is applied to nuclei 64Ge and 74Se. Both of their positive and negative parity bands are obtained. The calculated energy spectra are consistent with experimental spectra well.
KGeneral is an online program based on ROOT package, which reads files from KLOEGlobal at the KLOE to monitor the KLOE experiment. It displays statistics from the KLOE detector with its electronics, processed data of DAQ monitoring program and DAΦNE machine control systems. KGeneral uses the item "Custom" to display graphs in which users are interested, the vertical and horizontal sliders magnifying graphs to trace and monitor quality of the data in detail. KGeneral is developed with OOP technique by using C++language. Data tables in files are listed, class design and its inherit relations in KGeneral are described. Comments on effective references of the ROOT classes are made according to our experiences.
TEXONO collaboration adopts CsI(T1) crystal calorimeter to measure the energy spectrum and abnormal magnetic moment of reactor neutrino. The paper describes the design of shielding; the main source of backgrounds and the Monte Carlo Simulation based on the GEANT3 code for the effect of the shielding.
In this paper, the upgraded BPM system including the data acquisition instrumentation of HLS in NSRL phase II project are described in details. In the upgraded BPM system, we wash out the multiplexer relay switch system for signal transmit formerly and adopt paratactic signal processing. Bergoz's analog BPM modules and modular VXI instruments are adopted for BPM signal processing and data acquisition in order to provide stable and credible performance. The Lab VIEW developement environment not only provides good hardware controls but also promotes the development efficiency. After upgrade the new COD system with repetition error≤10μm and resolution 1μm is achieved in routine operation. Lately using the upgrade COD system we have completed the measurement of dispersion and one of magnetic field center for quadrupole magnet in beam based alignment(BBA) with local bump orbit, and have processed the experiment of global close orbit correction for HLS storage ring.
There is high electromagnetic noise radiation in Hefei Light Source (HLS) klystron gallery, which is from pulse discharging of thyratron modulator. This paper expounds the components of discharging circuit of HLS modulator. On the basis of it, the paper analyses the generating of discharging noise of klystron modulator and puts forward the method about reducing discharging noise of klystron modulator.
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