Measurements of coherent tune shift and head-tail growth rates at the SPS
نویسندگان
چکیده
Measurements of the coherent tune shifts with intensity and of head-tail growth rates have been performed with single proton bunches in the SPS, at 26 GeV. From these measurements, the real and imaginary part of the transverse impedance can be estimated. Together with earlier and future measurements, this will be used to experimentally document and follow up the effect of the impedance improvements on the SPS as injector to the LHC. A reproducibility at the 20% level was achieved for the value of the effective vertical impedance inferred from the coherent tune-shift measurements.
منابع مشابه
Measurements of SPS Single - Bunch Coherent Tune Shifts and Head - Tail Growth Rates in the Year 2001
Measurements of transverse oscillations of single bunches of protons in the SPS at 26 GeV are described. They are used to monitor the transverse impedance of the SPS. There has been a major effort to reduce the SPS impedance in the last winter shutdown, by shielding of most pumping ports and removal of obsolete (lepton) components. In fact, a significant reduction in the coherent tune shift wit...
متن کاملEUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH European Laboratory for Particle Physics THE ELECTRON CLOUD INSTABILITY OF THE LHC BEAM IN THE CERN SPS
The electron cloud induced by the LHC beam in the SPS occurs mainly in the dipoles and it is responsible for strong transverse instabilities. In the horizontal plane a coupled bunch mode instability develops in a few tens of turns at injection. Tune shift measurements, mode number and phase space analyses have been performed at different energies and provide information about the electron cloud...
متن کاملEUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH AB-Note-2006-007 ABP Coherent and Incoherent Tune Shift Induced by the Nonlinear Flat-Chamber Resistive-Wall Wake Field with an Application to the LHC Collimator Experiment in the SPS
We derive formulae for the coherent and incoherent tune shift due to the nonlinear resistive-wall wake field for a single beam travelling between two parallel plates. The theoretical predictions are compared with measurements performed on an LHC prototype collimator during the 2004 SPS run. We show that the tune shift derived from the nonlinear wake field yields a better agreement with the meas...
متن کاملHorizontal Instability in the KEKB HER
After a brief introduction to the problem, I study several aspects related to the horizontal instability in the KEKB HER, namely resistive-wall instability, ion trapping and ion instability, ion losses and the associated modification of the fast beam-ion instability, measurements of coupledbunch oscillations and their simulation assuming they are driven by ions, resistive wall, or electron clou...
متن کاملTransverse Performance of the Proton Beam Delivered by the Cern Ps Complex for the Future Lhc
The performance of the CERN LHC will depend heavily on the high-brightness beam delivered by the injector chain. In 1999, after completion of the programme of hardware upgrades of the PS Complex, a major effort was devoted to producing a proton beam with the nominal transverse characteristics foreseen for LHC operation. This paper focuses on the different beam dynamics issues encountered during...
متن کامل