Research in Particle Beam Physics and Accelerator Technology of the Collaboration IKP Forschungszentrum Jülich & JINR A.N. Parfenov for the Collaboration 5th Workshop on The Scientific cooperation between German Research Centres and JINR Dubna, January 2005

Contents 1. Electron cooling in COSY 2. Numerical simulation of the particle beam dynamics in storage ring 3. Beam profile monitor based on light radiation of excited atoms of residual gas

1.Electron cooling in COSY 1.Electron cooling in COSY (1999 – 2004) Three effects limiting stored beam intensity have been discovered and studied: beam losses provoked by nonlinear electric field of the cooling electron beam (”large betatron amplitudes”); coherent instability development in the cooled proton beam; “three components instability” related to the storage of residual gas ions in the cooling electron beam. Methods of “the treatment” developed:  damping of vertical coherent oscillations with feedback;  cleaning of the stored ions.

1.Electron cooling in COSY (continued) Vertical Feedback system in COSY Gain [db] = mA Feedback gain optimization Vert. PU BTM Sum PU Hor. PU The results of electron cooling development in COSY :  Beam intensity increased by 2 times;  Parasitic halo in accelerated beam became negligible (minimization of background at detectors!);  Decrease of beam emittance and momentum spread. Precise measurement of  -mezon mass has been fulfilled!

2. Numerical simulation of the particle beam circulating in storage ring The code BETACOOL for numerical simulation of the particle beam dynamics has been developed. It takes into account numerous effects, which present in reality: - the ring lattice (focusing system), - space charge of the circulating beam, - electron cooling, - intrabeam scattering, - internal target influence, The code is being used in several laboratories for beam dynamics simulation – IKP FZJ (COSY), BNL (RHIC), CERN (LEIR), GSI-IKP FZJ (project HESR in FAIR),...

2. Numerical simulation of the particle beam circulating in storage ring (continued) An example: The results of Molecular Dynamics simulation of the ion beam parameters evolution in ESR (GSI) during electron cooling process – “the trajectories” in the phase space of ion beam emittance and momentum spread. simulation New criterion of the ordering (“crystallisation”) and the equilibrium point ESR (GSI) experiment

3. Beam position and profile monitor (BPPM) based on light radiation of exited residual gas atoms Advantages The spatial resolution is not limited by the beam intensity (the beam space charge field does not influence a photon trajectory). BPPM can work in high level magnet fields where an application of ionization methods is limited. -The time resolution is much better than the resolution of ionization based systems. The main disadvantage of the photon registration method is its rather low sensitivity because atomic excitations cross-section is smaller than the ionization one. However, this disadvantage practically does not limit application of the method under specific conditions.

The proton beam of ~10 10 intensity at the energy of 1.2 GeV of ~4 cm diameter of ~100 ns duration has passed through the gas target filled with N 2 of pressure from to mbar.

Nitrogen of p=0.5 mbar Proton beam of 1.2 GeV N p ~ 5 x10 9

Conclusions The results obtained by FZJ – JINR collaboration in the field of particle beam physics and accelerator technology are of significant practical importance. 1)The electron cooling development at COSY has brought already interesting scientific results in particle physics and is of high importance for future accelerator projects. 2) Creation of the BETACOOL code has allowed to perform numerical simulation of particle beam dynamics in different cooler-storage rings and is being used presently for development of FAIR project at GSI. 3) Elaboration of The Optical Beam Position and Profile Monitor promises to provide accelerator technique with a new efficient diagnostic tool, which undoubtedly will have numerous applications.