Measurement of HERA's Central RF Frequency

Hoffstaetter, G. H.; Willeke, F.; Holzer, B.; Meseck, A.

Report/Contribution to a conference proceedings

PUBDB-2016-04121

Measurement of HERA's Central RF Frequency

Hoffstaetter, G. H. (Corresponding author) ; Holzer, B.Extern* ; Willeke, F. ; Meseck, A.DESY*

2002

The 8th European Particle Accelerator Conference, EPAC2002, Paris, France, 3 Jun 2002 - 7 Jun 2002 398-400 (2002) [10.3204/PUBDB-2016-04121]

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Please use a persistent id in citations: doi:10.3204/PUBDB-2016-04121

Report No.: DESY-M-02-01T

Abstract: For the HERA luminosity upgrade the horizontal emittance of the electron beam was reduced from 41 nm to 22 nm firstly by an increased quadrupole focusing in the arcs’ FODO structures and secondly by a change of the damping partition numbers by means of an rf frequency shift.The stronger focusing alone, which increases the phase advance per FODO cell from 60 to 72 degrees, would only reduce the emittance to 35 nm. It was therefore critical for the luminosity upgrade to make sure that there is sufficient room in the damping window for increasing the frequency of HERA’s 500 MHz system by the required 300 Hz. For this purpose HERA’s rf frequency had to be compared to the central frequency of the ring, for which the design orbit goes through the center of the quadrupoles. Since the accuracy of most methods of finding the central frequency is quite limited, we have used 7 different methods. Their results and their accuracies are compared in this paper.

Keyword(s): talk: Paris 2002/06/03 ; electron p: storage ring ; luminosity: upgrade ; RF system: resonance ; measurement: resonance ; quadrupole lens: special focusing ; beam: absorption ; beam emittance ; DESY HERA Stor