Instrumentation for the study of low emittance tuning and beam dynamics at CESR

Abstract

A: The Cornell Electron-positron Storage Ring (CESR) has been converted from a High Energy Physics electron-positron collider to operate as a dedicated synchrotron light source for the Cornell High Energy Synchrotron Source (CHESS) and to conduct accelerator physics research as a test accelerator, capable of studying topics relevant to future damping rings, colliders and light sources. Some of the specific topics that were targeted for the initial phase of operation of the storage ring in this mode for CESR as a Test Accelerator (CesrTA) included 1) tuning techniques to produce low emittance beams, 2) the study of electron cloud development in a storage ring and 3) intra-beam scattering effects. The complete conversion of CESR to CesrTA occurred over a several year period, described elsewhere [1][2][3]. In addition to instrumentation for the storage ring, which was created for CesrTA, existing instrumentation was modified to facilitate the entire range of investigations to support these studies. Procedures were developed, often requiring coordinated measurements among different instruments [4]. This paper describes the instruments utilized for the study of beam dynamics during the operation of CesrTA. The treatment of these instruments will remain fairly general in this paper as it focusses on an overview of the instruments themselves. Their interaction and inter-relationships during sequences of observations is found in a companion paper describing the associated measurement techniques. More detailed descriptions and detailed operational performance for some of the instrumentation may be found elsewhere and these will be referenced in the related sections of this paper.

Accelerator Design for the CHESS-U Upgrade

“…CESR is well-instrumented for a multitude of beambased measurement techniques, thanks to the CesrTA program. Details are documented elsewhere [20]. A few highlights are noted here.…”

Measurement techniques for low emittance tuning and beam dynamics at CESR

“…The vast majority of the measurements of tune shift have been taken in two different configurations. In the first horizontal and vertical pinger magnets [4] are independently excited to deflect all of the bunches, causing them to execute betatron oscillations in the respective transverse plane. CBPM turn-by-turn data, triggered just before the pingers fire, is acquired for all of the bunches within the train.…”

“…For instability studies, the bunch-by-bunch position measurements are accomplished by a BPM detector connected to one of CESR's original relay-based BPM system processors, which in turn passes its video output signal to a spectrum analyzer in the control room. (See reference [4] for the description of the hardware.) BPM33W, which is located at a high vertical beta point, has generally been used as the detector for these observations.…”

“…A number of specific instruments were developed for CesrTA. Much of the pre-existing instrumentation was modified to accommodate the scope of these studies and these are described in a companion paper [4]. To complete this research, a number of procedures were developed or modified, often requiring coordinated measurements among different instruments [5].…”