Methods of computer processing of experimental data on the intensity of bunches in synchrotrons

Methods of computer processing of experimental data on the intensity of bunches in synchrotrons for the purpose of receiving functional dependences from time during the accelerating cycle for a number of circulating particles and the mean-square length of a bunch are discussed. Examples of such dependences for the beam at the nuclotron (JINR) and PSB (CERN) are presented.     

Transverse damping systems in modern synchrotrons

Transverse feedback systems for suppression of transverse coherent beam oscillations are used in modern synchrotrons for preventing the development of transverse instabilities and damping residual beam oscillations after injection. Information on damper systems for the Large Hadron Collider (LHC; CERN, Geneva) and the accelerator complex FAIR (GSI, Darmstadt) is presented. The project for the LHC is being performed at the Laboratory of Particle Physics of the Joint Institute for Nuclear Research in collaboration with CERN. The information concerning the state of the project and the plans of its completion at the LHC is given. The results of the first design activity on transverse damping systems at the SIS100 and SIS300 synchrotrons, to be created in the framework of the new international project FAIR, are presented.     

Modeling of a microscopic optical pion-nucleon potential at energies in the (3, 3)-resonance region and nuclear-matter effect on the pion-nucleon amplitude

Differential cross sections for elastic pion scattering on a number of nuclei at energies between 130 and 290 MeV are calculated. For this purpose, use is made of a microscopic optical pion-nucleus potential that was obtained on the basis of the Glauber theory of high-energy scattering and which is determined by the density distribution of pointlike target nucleons and by the pion-nucleon scattering amplitude. The calculation of the cross sections in question is based on solving the respective relativistic wave equation. Three parameters of the pion-nucleon amplitude are fitted in performing a comparison with experimental data. These are the total cross section for pion-nucleon scattering, the ratio of the real to the imaginary part of the forward pion-nucleon scattering amplitude, and the slope parameter. The resulting values of these parameters are then compared with their counterparts for scattering on free nucleons. The character of nuclear-matter-induced changes in these parameters is studied.     

The Use of a Damping System in a Synchrotron for the Short-Time Excitation of Coherent Oscillations of Particles

Physics of Particles and Nuclei Letters - The possibility of applying a damping system of coherent transverse beam oscillations in a synchrotron using a positive feedback mode for the short-time...     

Beam dynamics in synchrotrons with digital wideband transverse feedback systems

Current researches on beam dynamics in synchrotrons with digital wideband transverse feedback systems are reviewed. Particular attention is given to quantitative and qualitative regularities in frequency shifts and decrements of coherent betatron oscillation damping when feedback loop signals are digitally processed. Theoretical predictions are compared with the experimental data obtained at the Large Hadron Collider.     

Beam stability in synchrotrons with digital transverse feedback systems in dependence on beam tunes

The beam stability problem in synchrotrons with a digital transverse feedback system (TFS) is studied. The TFS damper kicker (DK) corrects the transverse momentum of a bunch in proportion to its displacement from the closed orbit measured at the location of the beam position monitor (BPM). It is shown that the area and configuration of the beam stability separatrix depend on the beam tune, the feedback gain, the phase balance between the phase advance from BPM to DK and the phase response of the feedback chain at the betatron frequency.     

Longitudinal beam emittance blow-up caused by injection errors in synchrotrons with a longitudinal feedback system

The problem of longitudinal beam emittance blow-up caused by injection errors in synchrotrons with a longitudinal feedback system is studied. The obtained results are used to estimate parameters of a longitudinal feedback system.     

Damping of coherent betatron oscillations of a charged particle beam in synchrotrons with a feedback system

Decisions of a delay differential equation which describes the dynamics of a charged particle beam in the smoothed approach in synchrotrons with a feedback system are analyzed. Features of the decisions for frequency shifts and decrements of coherent betatron oscillation damping caused by a signal delay in the feedback loop are revealed.     

Transient beam response in synchrotrons with a digital transverse feedback system

The transient beam response to an external impulse force in synchrotrons with a digital transverse feedback system is studied. The experimental data on damping coherent transverse oscillations of bunch excited by a discrete-time unit impulse in the Large Hadron Collider (LHC) are analyzed. Good agreement between the measured and theoretically predicted decrements has been obtained. A method of feedback fine tuning based on measurements of the bunch response to a harmonic excitation impulse is discussed.