Speaker
Bernhard Holzer
(Deutsches Elektronen-Synchrotron (DESY)-Unknown-Unknown)
Description
HERA was designed as electron (or positron) - proton collider for maximum energies of 30 GeV for the leptons and 920 GeV for the proton beam. Due to this large difference in beam energy, the machine had to be built as two independent storage rings with common interaction regions at the collision points.
As a special feature of the machine, the different characteristics of the lepton and proton beams had to be considered: The electron beam - due to synchrotron radiation strongly determined by its emittance and thus characterized by a flat aspect ratio in the transverse planes, had to be well matched to the “round” proton beam at the two interaction points. In addition, the dynamic influence of the electron mini beta magnets at the interaction region on the proton optics and orbit, as well as the effect of the stray fields of the proton magnets on the electron beam dynamics had to be compensated carefully to establish well defined beam optics during the complete machine cycle and to guarantee matched beam sizes of the electron and proton beam during beam collisions. Starting from very basic measurements of the beta function in the beginning of the HERA runperiod, modern tools have been developed over the years and applied to measure and optimise the optical parameters like beta function, dispersion and effective beam size at the IP.
The talk will give an introduction into the lattice of the two HERA storage rings, present an overview about the historical development of the optics measurements and summarise the results.
