No abstract available

[en] Using about 3 fb^-1 of data collected with the CLEO II detector at the Cornell Electron Storage Ring, CESR, on and just below the Υ(4s) resonance, the authors have looked for evidence of B mesons decaying into the charmed strange baryon Ξ_c. They present the first observation of B mesons decaying into Ξ_c⁰ and Ξ_c⁺, with Ξ_c⁰→Ξ^-π⁺, and Ξ_c⁺→Ξ^-π⁺π⁺

[en] The sum-peak method was applied to calibrate four ⁶⁰Co sources in the range of 25-350 kBq. An HPGe-based γ-ray spectroscopy system was used, and the effects of the angular correlation and pulse pile-up were corrected, and are discussed. The correction for the angular correlation was obtained from a theoretical calculation, while the pulse pile-up effect was corrected using a new extrapolation technique based on the pile-up measurements by varying the shaping time of the amplifier. The determined radioactivities were within 2% deviation from the values reported by the supplier and the associated uncertainties were less than 2%. The observed consistency was obtained under the experimental condition of keeping the total counting rate ≤15 kcps

[en] The precession angle of a polarization vector is calculated for a positively charged short-lived baryon channeling between single-crystal planes. When very energetic polarized baryons are produced such that the production plane of the baryon is almost parallel to the crystal plane, it is shown that the interaction of the polarization with inhomogeneous electric fields inside the crystal can be neglected from the equation of motion of the particle. In this case, the equation of motion of the polarization vector becomes the same as when the electric field is homogeneous. It is also shown that when the crystal is bent perpendicular to the planar direction, the precession angle of the polarization vector of short-lived baryons can be expressed as ΔTHETAsub(R)sup(tau)=γ²[(2-g+g/γ²)]upsilonrhotau/2R under the same condition as above, where γ is the Lorentz factor, g the g factor of the magnetic moment, R the bending radius of the crystal and tau the lifetime of the particle. It is also shown that in some cases this precession should be large enough to determine the magnetic moment of short-lived particles, such as the charmed baryon Λsub(c)⁺. (orig.)

[en] The thickness of metal thin foil samples are measured in the target chamber of -10 .deg. C beam port of the accelerator mass spectrometer in Seoul National University[1,2]. Carbon ion beam is used in the experiments, and the measured spectra of Au, Ag, Cu samples are analyzed by using the computer code SIMNRA[3] in the RBS method. The measurement system and analysis method are confirmed by using the standard sample Au, and the thickness of unknown sample, Ag, Au are determined. The thickness are determined within about 3% in the standard sample

[en] The authors present here some design considerations for a possible experiment at the SSC fixed-target program. Estimates show that a precession angle of 1 radian can be achieved using a 5 cm long tungsten crystal. When a charged particle is channeled between planes of a bent single crystal, the induced magnetic field due to the motion of the particle in a non-uniform strong electric field of the crystal will cause the particle to precess in moving through the crystal. This effect may be utilized to measure the magnetic moment of short-live charmed baryons. This measurement is better performed at higher energies because the flight paths are longer to allow better measurements of the precession angle. The authors present here some estimates on the feasibility of this experiment at the SSC

[en] We have measured the inclusive branching ratio for B→psiX to be (1.09 +- 0.16 +- 0.21)%, and the exclusive branching ratios for B^-→psiK^- and B-bar ⁰→psiK-bar /sup */⁰ to be (0.09 +- 0.05)% and (0.41 +- 0.18)%, respectively. The mass difference between neutral and charged B mesons is 1.1 +- 2.1 MeV, while the difference between the mass of Υ(4S) and twice the mean B-meson mass is 18.5 +- 3.0 MeV. The psi momentum distribution implies a substantial two-body decay (in agreement with direct measurements), but also some combination of B→psiX with M/sub X/>1.5 GeV, and B→psi'X

[en] For the analysis of high-order harmonics generated in a long gas jet by intense chirped femtosecond laser pulses, calculations of the laser propagation and harmonic generation were performed in terms of a nonadiabatic three-dimensional model. The self-guided propagation, observed at the conditions of bright harmonic generation, was confirmed by the model calculations. When using negatively chirped pulses, the calculated distribution of the harmonic field is spatially and spectrally confined, being generated on axis with a narrow spectral profile. The positively chirped pulses generate broad spectral distribution on axis, and narrow off axis, but in the latter case with a large emission angle. The estimation of harmonic beam divergence agreed well with experimentally measured data, showing the lowest divergence at the conditions of the brightest harmonic generation. Spectral, temporal, and spatial modifications of the propagated laser pulse are found to influence decisively the single-atom response and ultimately the harmonic field, providing a coherent picture of harmonic generation

[en] Use of a bent single crystal to split off a small fraction of an incident high energy (400 to 800 GeV) particle beam has been demonstrated. The question which remains to be answered is: Will radiation damage effects deteriorate crystal performance in too short a time for practical application. Single Si crystals exposed to 10¹⁷ high energy protons per cm² have been examined previously using low energy (1.5 to 3.0 MeV) helium ion backscattering. The amount of radiation damage indicated by this low penetration technique was very small. This paper reports verification that such an exposed crystal still channels high energy particles. Furthermore, results using helium ion backscattering following an irradiation to 10¹⁸/cm² predict no deterioration in channeling performance

[en] Full text: Thermal analysis was performed for a Ti drive-in target of a D-D neutron generator. Numerical calculation was the only feasible way to obtain the information of the target temperature, since it was very difficult to measure the target temperature during neutron generation due to high voltage being applied to the target. Computational fluid dynamics code CFX-5 was used in this study. In order to define the heat flux term for the thermal analysis, the current profile of the ion beam was measured. The one-dimensional, integrated current profile was measured by using a single slit and a Faraday cup. The measured current profile was transformed into the axially symmetric two-dimensional distribution function by using the Abel inversion, which had the two-dimensional Gaussian function shape. Temperature distribution in the target was calculated at the operating condition. The influence of operational parameters like the ion beam energy, current, coolant mass flow rate and coolant inlet temperature on the target temperature was investigated