11580844
Summary report of the impedance and instability subgroup
This subgroup discussed several technical issues facing the BTCF (Beijing tau-charm factory). Most of these are R and D issues to be performed before a construction start. The two uncertainties facing the B-factories and the BTCF alike, namely the transient ion instability and the photo-electron instability are much weaker in the BTCF. Another uncertainty concerns the monochromator scheme, for which a round of parameters optimization is called for. The R and D issues can be collected into a long list. These discussions are by no means exhaustive, but are listed below as a summary of this report: (1) impedance policing is to be established; (2) single bunch instability is marginally acceptable; (3) beam-beam effects is to be considered together with microwave instability to optimize the overall design; (4) microwave power is a new issue which needs attention; (5) trapped modes need attention; (6) aluminum antechamber vacuum chamber design is recommended; (7) electrostatic separators need to be designed to minimize the microwave power generation; (8) dust particles need attention.
39781210
Fringe Field Interference Research on Quadrupole-Sextupole Assembly in BEPC-II
Many compact accelerators are increasingly popular nowadays. The studies on fringe field interference effect between adjacent magnets are becoming more important. Based on the 3-D multipole expansion technique, the integrated gradient deviation in a quadrupole magnet due to the appearance of neighboring sextupole is investigated. The quad-sext interference effect had been evaluated for BEPC-II. The relative impacts on accelerator tune shift will be obtained further and confirmed by experiments finally.
209441918
BRIEF OVERVIEW OF PARTICLE ACCELERATORS IN CHINA
A brief overview of the main particle accelerators in China is given. New projects in the near future are also simply described.
123202707
Chromaticity in Strong Focusing Accelerators and Storage Rings
The chromaticity formulae with accuracy to the first-order in momentum deviation in strong focusing accelerators & storage rings have been derived. It has been found that the edge magnetic field effects must be taken into account, otherwise the resultant errors introduced will be appreciable which increase rapidly with the decrease in machine size. They can not be neglected especially for proton and antiproton accumulators due to the very large momentum spread of the beams accumulated in them.
67785720
AN ANTI-SYMMETRIC LATTICE FOR HIGH-INTENSITY RAPID CYCLING SYNCHROTRONS.
Rapid cycling synchrotrons (RCSs) are used in many high power facilities like spallation neutron sources and proton drivers to accumulate and accelerate proton beams. In such accelerators, beam collimation plays a crucial role in reducing the uncontrolled beam loss. Furthermore, injection and extraction sections often need to reside in dispersion-free regions to avoid couplings; sizeable drift space is needed to house the RF accelerating cavities; long, uninterrupted straights are desired to ease injection tuning and to raise collimation efficiency. Finally, the machine circumference needs to be small to reduce construction costs. In this paper, we present a lattice satisfying these needs. The lattice contains a drift created by a missing dipole near the peak dispersion to facilitate longitudinal collimation. The compact FODO arc allows easy orbit, tune, coupling, and chromatic correction. The doublets provide long uninterrupted straights. The four-fold lattice symmetry separates injection, extraction, and collimation to different straights. This lattice is adopted for the China Spallation Neutron Source (CSNS) synchrotron [1].
124386868
The Application of Adiabatic Theorem to the Beam Dynamics in Accelerators
In this paper, the adiabatic criterion and the formulae for calculating the increment of adiabatic invariant due to the nonadiabatic change of paramters in Hamiltonian are derived and we have found that this increment is quite small, even in the case where the Landau's adiabatic criterion[1] is violated.
126424369
η and η' physics at BESIII
125315096
eta(c) physics at BES III
An introduction for eta(c) physics research is presented in this paper, which shows that the mechanism of eta(c) decays can't be. well described by current theoretical models and detailed experimental measurements need to be done with larger eta(c) sample. Based on the expected J/psi and psi' events taken with the planed BES III detector in one year, the eta(c) physics researches are discussed extensively, including the measurements of branching fractions of different final states, the search for new decay, modes, precision measurements of mass and width, and the search for rare decays. At last, the study of eta'(c) decays is also discussed briefly.
112023627
Charm Fragmentation Function and Charm Fragmentation Fractions at ZEUS
11750018
Measurement of the charm fragmentation into D* mesons at HERA
The charm fragmentation function has been measured with the H1 and ZEUS detectors at HERA in the deep inelastic scattering and photoproduction regimes. The measured function has been compared to different fragmentation models implemented in leading-logarithm Monte Carlo simulations and next-to-leading-order calculations.
123432115
Progress in light hadron spectroscopy at BESIII
Based on the 225 million J / ψ events and 106 million ψ ′ events taken at the BESIII detector, the recent results on light hadron spectroscopy are presented, including the partial wave analysis of J / ψ → γ p p ¯ and ψ ′ → p p ¯ η , confirmation of X(1835) and observation of two new resonances in J / ψ → γ π + π − η ′ , observation of a new resonance X(1870) in J / ψ → ω π + π − η and the first observation of isospin-violating decay mode of η ( 1405 ) → f 0 ( 980 ) π 0 .