Diamond, Oxfordshire
JAI, Oxford
The Diamond light source started operation for users in January 2007. With the successful commissioning of the nominal optics, delivering a 2.75 nm emittance beam at 3 GeV, we now routinely provide the users with a 250 mA beam with a lifetime of >20 h, exceeding the minimum specified current-lifetime product of 3000 mAh. Driven by the necessity to guarantee a correct implementation of the nonlinear optics, a significant experimental and theoretical effort is ongoing to understand and improve the nonlinear beam dynamics in the storage ring. The necessity to control the nonlinear beam dynamics is even more urgent with the installation of a large number of small gap (5 mm) in-vacuum insertion device and the need to control the injection efficiency with Top-Up operation. We report here the present status of the analysis of the nonlinear beam dynamics and the main experimental results.
CERN, Geneva
After a intense and hectic code development during the LHC design phase the MAD-X program (Methodical Accelerator Design – Version X) is going through a period of code consolidation. To this end the development on the core has been frozen and most effort are concerned with a solid debugging in view of a trustworthy production version for the LHC commissioning. On the other hand, the demand on further code development from the LHC pre-accelerators and CLIC are dealt with PTC related parts of the code where the implementation is in full swing. Having reached a mature state of the code the question arises what kind of future can be envisaged for MAD-X.
IHEP Beijing, Beijing
The luminosity of BEPCII (the upgrade project of Beijing electron-positron collider) have reached 3.0× 1032 cm-2s-1@1.89GeV in May 2009. In this papaer we'll compare the beam-beam simulation results with the real machine. In the case the single bunch current is lower than 8mA, the simulation concides well with the real. Some phenomenon related to synchro-betatron resonances during machine tuning and simulation is shown. The tune is close to half integer help us increase luminosity, however the detector background increases at the same time. It is believed that the beam-beam dynamic effect result in the drop of the dynamic aperture. We also study the possible luminosity contribution from the crab waist scheme in BEPCII.
STFC/RAL/ISIS, Chilton, Didcot, Oxon
The ISIS Facility at the Rutherford Appleton Laboratory in the UK produces intense neutron and muon beams for condensed matter research. It is based on a 50 Hz proton synchrotron which accelerates ~3·1013 protons per pulse (ppp) from 70 to 800 MeV, corresponding to beam powers of ~0.2 MW. Studies are under way for major upgrades in the Megawatt regime. Underpinning this programme of operations and upgrades is a study of the high intensity effects that impose limitations on beam power. The behaviour of the beam in the 50 Hz rapid cycling synchrotron (RCS) is largely characterised by high space charge levels and the effects of fast ramping acceleration. High intensity effects are of particular importance as they drive beam loss, but are not fully understood with only limited analytical models available. This paper reviews several methods by which these effects are explored numerically on ISIS, and compares them where possible with experimental or analytical results. In particular we outline development of a new space charge code Set, which is designed to address key issues on ISIS and similar RCS machines.
SLAC, Menlo Park, California
In a multi-bunch high current storage ring, beam generated fields couple strongly into the RF cavity coupler structure when beam arrival times are in resonance with cavity fields. In this study the integrated effect of beam fields over a several thousand RF periods is simulated for the complete cavity, coupler, window and waveguide system of the PEP-II B-factory storage ring collider. We show that the beam generated fields at frequencies corresponding to several bunch spacings for this case gives rise to high field strength near the ceramic window and could limit the performance of future high current storage rings such as PEP-X or Super B-factories.