204174153
Combined chiral dynamics and MIT bag model study of strong Sigma(*) Q-->LambdaQpi decays
117250608
Study of rare $B^+_{c} \to D_{d,s}$ + lepton anti-lepton decays
We study the rare decays of $B_c^+\to D_{q}^{(*)+}l\bar{l}$ ($q=d,s$ and $l=\nu_l,e,\mu,\tau)$ in the standard model. The form factors are evaluated in the light front and constituent quark models, respectively. We find that the decay branching ratios calculated in the two models for $B_c^+\to D^+_q l\bar{l}$ agree well with each other, whereas those for $B_c^+\to D_q^{*+}l\bar{l}$ are different.
118628184
Model-independent analysis for determining mass splittings of heavy baryons
We study the hyperfine mass differences of heavy hadrons in the heavy quark effect theory. The effects of one-gluon exchange interaction are considered for the heavy mesons and baryons. Based on the known experimental data, we predict the masses of some heavy baryons in a model-independent way.
12196534
Mesonic form factors and the Isgur-Wise function on the light front
Within the light-front framework, form factors for P{r_arrow}P and P{r_arrow}V transitions (P denotes a pseudoscalar meson, V a vector meson) due to the valence-quark configuration are calculated directly in the entire physical range of momentum transfer. The behavior of the form factors in the infinite quark mass limit are examined to see if the requirements of heavy-quark symmetry are satisfied. We find that the Bauer-Stech-Wirbel-type light-front wave function fails to give a correct normalization for the Isgur-Wise function at zero recoil in P{r_arrow}V transition. Some of the P{r_arrow}V form factors are found to depend on the recoiling direction of the daughter mesons relative to their parents. Thus the inclusion of the nonvalence contribution arising from quark-pair creation is mandatory in order to ensure that the physical form factors are independent of the recoiling direction. The main feature of the nonvalence contribution is discussed. {copyright} {ital 1997} {ital The American Physical Society}
118480874
Study of quark distribution amplitudes of 1S and 2S heavy quarkonium states
In this paper, the quark distribution amplitudes of 1S and 2S heavy quarkonium states are studied in terms of Gaussian-type wave functions. The transverse momenta p⊥ integrals of the formulae for the decay constant are performed analytically. Then the quark distribution amplitudes are obtained. In addition, the ξ-moments are also calculated. After fixing the relevant parameters appearing in the quark distribution amplitude, the curves of the quark distribution amplitude for 1S and 2S heavy quarkonium states are plotted. Finally, the numerical results of this approach are compared with the other theoretical predictions.
111206305
STABILITY STUDY OF SUPERCONDUCTOR MAGNET POWER SUPPLIES AT TLS
In this paper, performance of three power supplies schemes driving the newly-developed Superconducting Wave Length Shifter Magnet at TLS is investigated. Due to the inherent structure of the Superconducting Magnet, the main and two accessory trimming power supplies are physically correlated with each others. Due to the inherent structure, in order to achieve high performance control of the magnet, slew rate control of the main power supply and the proper operation sequence have to be properly managed, otherwise, small current disturbance can occurs, which may degrade the stability of the performance of Superconducting Magnet.
122858718
Features of the magnetic field of a rectangular combined function bending magnet
Magnetic field features of the combined function bending magnet with dipole and quadrupole field components are essential for the successful operation of the electron beam trajectory. These fields also dominate the photon beam quality. The vertical magnetic field B/sub y/(x,y) calculation is performed by a computer code "MAGNET" at the magnet center (s=0). Those results are compared with the 2-D field measurement by the Hall probe mapping system. Also detailed survey has been made of the harmonic field strength and the main features of the fundamental integrated strength, effective length, magnetic symmetry, tilt of the pole face, offset of the field center and the fringe field. The end shims that compensate for the strong end negative sextupole field to increase the good field region for the entire integrated strength are discussed. An important physical feature of this combined function bending magnet is the constant ratio of dipole and quadrupole strength /spl int/Bds//spl int/Gds which is expressed as a function of excitation current in the energy range 0.6 to 1.5 GeV.
31380699
Design of a precise unit for the rotating coil measurement system
A precise rotating coil measurement system (RCS) is developed to characterize the magnetic field quality of the quadrupole (QM) and sextupole (SM) magnets in the Taiwan photon source (TPS). A measurement bench is designed to install the magnets easily and mount the rotating coil unit with high reproducibility. The fiberglass reinforced epoxy (FRP) measurement unit (F-unit) exhibits a large sag and mechanical error while it is 880 mm long. Therefore, a new graphite measurement unit (G-unit) with a printed circuit coil is adopted to reduce these errors. The rotating coil design and testing using a QM are also described.
115015433
Effectiveness of a Shielding Cabinet on the Storage-Ring Septum Magnet of Taiwan Light Source
Abstract To avoid a parasitic magnetic field in the stored beam, the pulsed-magnet system of Taiwan Photon Source (TPS) requires the stray field to be minute: the stray field from the storage-ring (SR) injection septum is required to be less than 0.1 % of the main field in the gap. The most common method to protect against a parasitic magnetic field is to use a highly permeable and conductive material, such as mu-metal. A 300-ms half-sine-wave pulse up to a current maximum 9922 A is supplied to a septum and results in an eddy-current loss in a magnet and a conductor during rapid charging of a magnet. Competition between an eddy-current effect and the magnetic permeability would produce a complicated phenomenon inside the magnetic-shielding screen and affect the shielding performance. We examined the performance of magnetic shielding of a shielding screen with OPERA 2D for varied geometry and thickness of the screen.
110858092
Vacuum commissioning for the SWLS absorber inside a kicker-chamber at TLS storage ring
A 6 T super-conducting wiggler, so called wavelength shifter, (SWLS) has been installed in the injection section of the 1.5 GeV Taiwan Light Source (TLS) electron storage ring. The intensive synchrotron radiation emitted from SWLS causes severe problems in the downstream kicker-chamber, such as radiation hitting on the ceramic parts, interfered non-uniform field and induced arcing from the absorber during kicker firing, etc. A new absorber, designed to solve those problems, has been developed and installed in the kicker-chamber downstream the SWLS. The earlier stage of vacuum commissioning shows a high pressure-rise, stimulated by the photons, localized near the head of absorber that seriously constrains the beam lifetime. However, the pressure reduces by continuous beam cleaning. The injection efficiency of the electron beam is not degraded much. The temperature rise on the downstream chambers, behaves not so according to the beam current, is kept within allowable values.